Begin adding support for tab mirroring via the MediaStream audio/video capturing

content/browser/renderer_host/media/media_stream_manager.cc

Index: content/browser/renderer_host/media/media_stream_manager.cc
diff --git a/content/browser/renderer_host/media/media_stream_manager.cc b/content/browser/renderer_host/media/media_stream_manager.cc
index 8194fde724332595de1996e35f27e6c6f4aa7e41..26bb149cdda5d2fb58c575552a76a1415643008a 100644
--- a/content/browser/renderer_host/media/media_stream_manager.cc
+++ b/content/browser/renderer_host/media/media_stream_manager.cc
@@ -11,6 +11,7 @@
 #include "base/logging.h"
 #include "base/rand_util.h"
 #include "base/win/scoped_com_initializer.h"
+#include "content/browser/browser_main_loop.h"
 #include "content/browser/renderer_host/media/audio_input_device_manager.h"
 #include "content/browser/renderer_host/media/media_stream_device_settings.h"
 #include "content/browser/renderer_host/media/media_stream_requester.h"
@@ -47,10 +48,8 @@ static std::string RandomLabel() {
 // Helper to verify if a media stream type is part of options or not.
 static bool Requested(const StreamOptions& options,
                       MediaStreamType stream_type) {
-  return (stream_type == content::MEDIA_STREAM_DEVICE_TYPE_VIDEO_CAPTURE &&
-          options.video) ||
-         (stream_type == content::MEDIA_STREAM_DEVICE_TYPE_AUDIO_CAPTURE &&
-          options.audio);
+  return (options.audio_type == stream_type ||
+          options.video_type == stream_type);
 }
 
 DeviceThread::DeviceThread(const char* name)
@@ -90,12 +89,10 @@ struct MediaStreamManager::DeviceRequest {
 
   DeviceRequest()
       : requester(NULL),
-        state(content::NUM_MEDIA_STREAM_DEVICE_TYPES, STATE_NOT_REQUESTED),
+        state(content::NUM_MEDIA_TYPES, STATE_NOT_REQUESTED),
         type(GENERATE_STREAM),
         render_process_id(-1),
         render_view_id(-1) {
-    options.audio = false;
-    options.video = false;
   }
 
   DeviceRequest(MediaStreamRequester* requester,
@@ -105,7 +102,7 @@ struct MediaStreamManager::DeviceRequest {
                 const GURL& request_security_origin)
       : requester(requester),
         options(request_options),
-        state(content::NUM_MEDIA_STREAM_DEVICE_TYPES, STATE_NOT_REQUESTED),
+        state(content::NUM_MEDIA_TYPES, STATE_NOT_REQUESTED),
         type(GENERATE_STREAM),
         render_process_id(render_process_id),
         render_view_id(render_view_id),
@@ -122,9 +119,7 @@ struct MediaStreamManager::DeviceRequest {
   int render_process_id;
   int render_view_id;
   GURL security_origin;
-  std::string requested_device_id;
-  StreamDeviceInfoArray audio_devices;
-  StreamDeviceInfoArray video_devices;
+  StreamDeviceInfoArray devices;
 };
 
 MediaStreamManager::EnumerationCache::EnumerationCache()
@@ -134,13 +129,10 @@ MediaStreamManager::EnumerationCache::EnumerationCache()
 MediaStreamManager::EnumerationCache::~EnumerationCache() {
 }
 
-MediaStreamManager::MediaStreamManager(
-    AudioInputDeviceManager* audio_input_device_manager,
-    VideoCaptureManager* video_capture_manager)
+MediaStreamManager::MediaStreamManager()
     : ALLOW_THIS_IN_INITIALIZER_LIST(
           device_settings_(new MediaStreamDeviceSettings(this))),
-      audio_input_device_manager_(audio_input_device_manager),
-      video_capture_manager_(video_capture_manager),
+      audio_manager_(NULL),
       monitoring_started_(false),
       io_loop_(NULL) {
   memset(active_enumeration_ref_count_, 0,
@@ -153,20 +145,6 @@ MediaStreamManager::~MediaStreamManager() {
   DCHECK(!io_loop_);
 }
 
-VideoCaptureManager* MediaStreamManager::video_capture_manager() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  DCHECK(video_capture_manager_);
-  EnsureDeviceThreadAndListener();
-  return video_capture_manager_;
-}
-
-AudioInputDeviceManager* MediaStreamManager::audio_input_device_manager() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  DCHECK(audio_input_device_manager_);
-  EnsureDeviceThreadAndListener();
-  return audio_input_device_manager_;
-}
-
 void MediaStreamManager::GenerateStream(MediaStreamRequester* requester,
                                         int render_process_id,
                                         int render_view_id,
@@ -197,21 +175,19 @@ void MediaStreamManager::CancelGenerateStream(const std::string& label) {
   if (it != requests_.end()) {
     // The request isn't complete.
     if (!RequestDone(it->second)) {
-      DeviceRequest* request = &(it->second);
-      if (request->state[content::MEDIA_STREAM_DEVICE_TYPE_AUDIO_CAPTURE] ==
-          DeviceRequest::STATE_OPENING) {
-        for (StreamDeviceInfoArray::iterator it =
-             request->audio_devices.begin(); it != request->audio_devices.end();
-             ++it) {
-          audio_input_device_manager()->Close(it->session_id);
+      DeviceRequest& request = it->second;
+      for (int i = content::MEDIA_NO_SERVICE + 1; i < content::NUM_MEDIA_TYPES;
+           ++i) {
+        const MediaStreamType stream_type = static_cast<MediaStreamType>(i);
+        if (request.state[stream_type] != DeviceRequest::STATE_OPENING) {
+          continue;
         }
-      }
-      if (request->state[content::MEDIA_STREAM_DEVICE_TYPE_VIDEO_CAPTURE] ==
-          DeviceRequest::STATE_OPENING) {
-        for (StreamDeviceInfoArray::iterator it =
-             request->video_devices.begin(); it != request->video_devices.end();
-             ++it) {
-          video_capture_manager()->Close(it->session_id);
+        for (StreamDeviceInfoArray::const_iterator device_it =
+                 request.devices.begin();
+             device_it != request.devices.end(); ++device_it) {
+          if (device_it->stream_type == stream_type) {
+            GetDeviceManager(stream_type)->Close(device_it->session_id);
+          }
         }
       }
       requests_.erase(it);
@@ -231,15 +207,10 @@ void MediaStreamManager::StopGeneratedStream(const std::string& label) {
       StopEnumerateDevices(label);
       return;
     }
-    for (StreamDeviceInfoArray::iterator audio_it =
-         it->second.audio_devices.begin();
-         audio_it != it->second.audio_devices.end(); ++audio_it) {
-      audio_input_device_manager()->Close(audio_it->session_id);
-    }
-    for (StreamDeviceInfoArray::iterator video_it =
-         it->second.video_devices.begin();
-         video_it != it->second.video_devices.end(); ++video_it) {
-      video_capture_manager()->Close(video_it->session_id);
+    for (StreamDeviceInfoArray::const_iterator device_it =
+             it->second.devices.begin();
+         device_it != it->second.devices.end(); ++device_it) {
+      GetDeviceManager(device_it->stream_type)->Close(device_it->session_id);
     }
     if (it->second.type == DeviceRequest::GENERATE_STREAM &&
         RequestDone(it->second)) {
@@ -257,18 +228,25 @@ void MediaStreamManager::EnumerateDevices(
     const GURL& security_origin,
     std::string* label) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  DCHECK(type == content::MEDIA_STREAM_DEVICE_TYPE_AUDIO_CAPTURE ||
-         type == content::MEDIA_STREAM_DEVICE_TYPE_VIDEO_CAPTURE);
+  DCHECK_LT(content::MEDIA_NO_SERVICE, type);
+  DCHECK_GT(content::NUM_MEDIA_TYPES, type);
 
   // Create a new request.
   StreamOptions options;
-  EnumerationCache* cache = NULL;
-  if (type == content::MEDIA_STREAM_DEVICE_TYPE_AUDIO_CAPTURE) {
-    options.audio = true;
-    cache = &audio_enumeration_cache_;
+  EnumerationCache* cache;
+  if (type == content::MEDIA_USER_AUDIO_CAPTURE) {
+    options.audio_type = type;
+    cache = &user_audio_enumeration_cache_;
+  } else if (type == content::MEDIA_USER_VIDEO_CAPTURE) {
+    options.video_type = type;
+    cache = &user_video_enumeration_cache_;
   } else {
-    options.video = true;
-    cache = &video_enumeration_cache_;
+    if (content::IsAudioMediaType(type)) {
+      options.audio_type = type;
+    } else if (content::IsVideoMediaType(type)) {
+      options.video_type = type;
+    }
+    cache = NULL;
   }
 
   DeviceRequest new_request(requester, options,
@@ -277,7 +255,7 @@ void MediaStreamManager::EnumerateDevices(
                             security_origin);
   new_request.type = DeviceRequest::ENUMERATE_DEVICES;
 
-  if (cache->valid) {
+  if (cache && cache->valid) {
     // Cached device list of this type exists. Just send it out.
     new_request.state[type] = DeviceRequest::STATE_REQUESTED;
     AddRequest(&new_request, label);
@@ -289,7 +267,9 @@ void MediaStreamManager::EnumerateDevices(
                    base::Unretained(this), cache, *label));
   } else {
     StartEnumeration(&new_request, label);
-    StartMonitoring();
+    if (cache) {
+      StartMonitoring();
+    }
   }
 }
 
@@ -318,17 +298,21 @@ void MediaStreamManager::OpenDevice(
 
   // Create a new request.
   StreamOptions options;
-  if (type == content::MEDIA_STREAM_DEVICE_TYPE_AUDIO_CAPTURE)
-    options.audio = true;
-  else
-    options.video = true;
+  if (content::IsAudioMediaType(type)) {
+    options.audio_type = type;
+  } else if (content::IsVideoMediaType(type)) {
+    options.video_type = type;
+  } else {
+    LOG(FATAL) << "Cannot handle request for MediaStreamType " << type;
+    return;
+  }
+  options.opt_device_id = device_id;

[wjia(left Chromium), 2012/09/03 15:54:17]

device_id doesn't belong to here. It should be in DeviceRequest as
requested_device_id. Based on how it's used, I don't see the need move it into
StreamOptions, either.

[miu, 2012/09/04 20:42:19]

Actually, I didn't move it from here into StreamOptions.  This was an
after-the-fact clean-up, since adding the new StreamOptions::opt_device_id field
made having the requested_device_id field redundant.

The real issue here is whether StreamOptions should have the new opt_device_id
field.

Let me explain what it is I'm trying to accomplish here: If you take a look at
the API proposal (see link in change description), you'll notice that user JS
code calls getTabMedia (analogous to getUserMedia) with a tab id.  Internally,
this would result in a call to GenerateStream, but I would like to restrict the
user's choice to one specific tab.  Therefore, I've added the opt_device_id
field to StreamOptions (for tabs, the device_id is the tab id).

Alternatively, I suppose I could remove opt_device_id from StreamOptions and go
a different route.  Ideas:

  1. Add an opt_device_id argument to GenerateStream().
  2. Add a separate method, GenerateStreamForDevice(<<same args as
GenerateStream, plus device_id>>)

These would require a lot more code changes, which is why I felt that simply
adding the opt_device_id field to StreamOptions was the right way to go.

What do you suggest I do here?

 
   DeviceRequest new_request(requester, options,
                             render_process_id,
                             render_view_id,
                             security_origin);
   new_request.type = DeviceRequest::OPEN_DEVICE;
-  new_request.requested_device_id = device_id;
 
   StartEnumeration(&new_request, label);
 }
@@ -358,8 +342,8 @@ void MediaStreamManager::StopMonitoring() {
   if (monitoring_started_ && !HasEnumerationRequest()) {
     base::SystemMonitor::Get()->RemoveDevicesChangedObserver(this);
     monitoring_started_ = false;
-    ClearEnumerationCache(&audio_enumeration_cache_);
-    ClearEnumerationCache(&video_enumeration_cache_);
+    ClearEnumerationCache(&user_audio_enumeration_cache_);
+    ClearEnumerationCache(&user_video_enumeration_cache_);
   }
 }
 
@@ -373,22 +357,16 @@ void MediaStreamManager::StartEnumeration(
     std::string* label) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
-  MediaStreamType stream_type = content::MEDIA_STREAM_DEVICE_TYPE_AUDIO_CAPTURE;
-  if (Requested(new_request->options, stream_type)) {
-    new_request->state[stream_type] = DeviceRequest::STATE_REQUESTED;
-    DCHECK_GE(active_enumeration_ref_count_[stream_type], 0);
-    if (!active_enumeration_ref_count_[stream_type]) {
-      ++active_enumeration_ref_count_[stream_type];
-      GetDeviceManager(stream_type)->EnumerateDevices();
-    }
-  }
-  stream_type = content::MEDIA_STREAM_DEVICE_TYPE_VIDEO_CAPTURE;
-  if (Requested(new_request->options, stream_type)) {
-    new_request->state[stream_type] = DeviceRequest::STATE_REQUESTED;
-    DCHECK_GE(active_enumeration_ref_count_[stream_type], 0);
-    if (!active_enumeration_ref_count_[stream_type]) {
-      ++active_enumeration_ref_count_[stream_type];
-      GetDeviceManager(stream_type)->EnumerateDevices();
+  for (int i = content::MEDIA_NO_SERVICE + 1; i < content::NUM_MEDIA_TYPES;
+       ++i) {
+    const MediaStreamType stream_type = static_cast<MediaStreamType>(i);
+    if (Requested(new_request->options, stream_type)) {
+      new_request->state[stream_type] = DeviceRequest::STATE_REQUESTED;
+      DCHECK_GE(active_enumeration_ref_count_[stream_type], 0);
+      if (active_enumeration_ref_count_[stream_type] == 0) {
+        ++active_enumeration_ref_count_[stream_type];
+        GetDeviceManager(stream_type)->EnumerateDevices();
+      }
     }
   }
 
@@ -411,22 +389,46 @@ void MediaStreamManager::AddRequest(
   (*label) = request_label;
 }
 
-void MediaStreamManager::EnsureDeviceThreadAndListener() {
+void MediaStreamManager::EnsureDeviceManagerStarted(
+    MediaStreamType stream_type) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  if (device_thread_.get())
-    return;
 
-  device_thread_.reset(new DeviceThread("MediaStreamDeviceThread"));
-  CHECK(device_thread_->Start());
+  if (!device_thread_.get()) {
+    device_thread_.reset(new DeviceThread("MediaStreamDeviceThread"));
+    CHECK(device_thread_->Start());
+  }
 
-  audio_input_device_manager_->Register(this,
-                                        device_thread_->message_loop_proxy());
-  video_capture_manager_->Register(this, device_thread_->message_loop_proxy());
+  if (!device_manager_[stream_type]) {
+    switch (stream_type) {
+      case content::MEDIA_USER_AUDIO_CAPTURE:
+      case content::MEDIA_TAB_AUDIO_CAPTURE:
+        if (!audio_manager_) {
+          audio_manager_ = content::BrowserMainLoop::GetAudioManager();
+        }
+        device_manager_[stream_type] =
+            new media_stream::AudioInputDeviceManager(audio_manager_,
+                                                      stream_type);
+        break;
+      case content::MEDIA_USER_VIDEO_CAPTURE:
+      case content::MEDIA_TAB_VIDEO_CAPTURE:
+        device_manager_[stream_type] =
+            new media_stream::VideoCaptureManager(stream_type);
+        break;
+      default:
+        LOG(FATAL) << "Cannot create device manager for invalid or "
+                   << "unsupported MediaStreamType " << stream_type;
+        return;
+    }
+    device_manager_[stream_type]->Register(
+        this, device_thread_->message_loop_proxy());
+  }
 
   // We want to be notified of IO message loop destruction to delete the thread
   // and the device managers.
-  io_loop_ = MessageLoop::current();
-  io_loop_->AddDestructionObserver(this);
+  if (!io_loop_) {
+    io_loop_ = MessageLoop::current();
+    io_loop_->AddDestructionObserver(this);
+  }
 }
 
 void MediaStreamManager::Opened(MediaStreamType stream_type,
@@ -439,17 +441,11 @@ void MediaStreamManager::Opened(MediaStreamType stream_type,
   std::string label;
   for (DeviceRequests::iterator request_it = requests_.begin();
        request_it != requests_.end() && request == NULL; ++request_it) {
-    if (stream_type == content::MEDIA_STREAM_DEVICE_TYPE_AUDIO_CAPTURE) {
-      devices = &(request_it->second.audio_devices);
-    } else if (stream_type == content::MEDIA_STREAM_DEVICE_TYPE_VIDEO_CAPTURE) {
-      devices = &(request_it->second.video_devices);
-    } else {
-      NOTREACHED();
-    }
-
+    devices = &(request_it->second.devices);
     for (StreamDeviceInfoArray::iterator device_it = devices->begin();
          device_it != devices->end(); ++device_it) {
-      if (device_it->session_id == capture_session_id) {
+      if (device_it->stream_type == stream_type &&
+          device_it->session_id == capture_session_id) {
         // We've found the request.
         device_it->in_use = true;
         label = request_it->first;
@@ -469,6 +465,9 @@ void MediaStreamManager::Opened(MediaStreamType stream_type,
   // they are.
   for (StreamDeviceInfoArray::iterator device_it = devices->begin();
        device_it != devices->end(); ++device_it) {
+    if (device_it->stream_type != stream_type) {
+      continue;
+    }
     if (device_it->in_use == false) {
       // Wait for more devices to be opened before we're done.
       return;
@@ -481,17 +480,36 @@ void MediaStreamManager::Opened(MediaStreamType stream_type,
     return;
   }
 
+  // Partition the array of devices into audio vs video.
+  StreamDeviceInfoArray audio_devices, video_devices;
+  for (StreamDeviceInfoArray::const_iterator device_it = devices->begin();
+       device_it != devices->end(); ++device_it) {
+    if (content::IsAudioMediaType(device_it->stream_type)) {
+      audio_devices.push_back(*device_it);
+    } else if (content::IsVideoMediaType(device_it->stream_type)) {
+      video_devices.push_back(*device_it);
+    } else {
+      NOTREACHED();
+    }
+  }
+
   switch (request->type) {
     case DeviceRequest::OPEN_DEVICE:
-      request->requester->DeviceOpened(label, (*devices)[0]);
+      if (content::IsAudioMediaType(stream_type)) {
+        request->requester->DeviceOpened(label, audio_devices.front());
+      } else if (content::IsVideoMediaType(stream_type)) {
+        request->requester->DeviceOpened(label, video_devices.front());
+      } else {
+        NOTREACHED();
+      }
       break;
     case DeviceRequest::GENERATE_STREAM:
-      request->requester->StreamGenerated(label, request->audio_devices,
-                                          request->video_devices);
+      request->requester->StreamGenerated(label, audio_devices, video_devices);
       NotifyObserverDevicesOpened(request);
       break;
     default:
       NOTREACHED();
+      break;
   }
 }
 
@@ -504,13 +522,20 @@ void MediaStreamManager::DevicesEnumerated(
     MediaStreamType stream_type, const StreamDeviceInfoArray& devices) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
-  // Only cache device list when there is EnumerateDevices request, since
+  // Only cache the device list when there is an EnumerateDevices request, since
   // other requests don't turn on device monitoring.
+  // NOTE: Caching only applies to the user audio/video capture devices.
+  EnumerationCache* cache;
+  if (stream_type == content::MEDIA_USER_AUDIO_CAPTURE) {
+    cache = &user_audio_enumeration_cache_;
+  } else if (stream_type == content::MEDIA_USER_VIDEO_CAPTURE) {
+    cache = &user_video_enumeration_cache_;
+  } else {
+    cache = NULL;
+  }
   bool need_update_clients = false;
-  EnumerationCache* cache =
-      (stream_type == content::MEDIA_STREAM_DEVICE_TYPE_AUDIO_CAPTURE ?
-       &audio_enumeration_cache_ : &video_enumeration_cache_);
-  if (HasEnumerationRequest(stream_type) &&
+  if (cache &&
+      HasEnumerationRequest(stream_type) &&
       (!cache->valid ||
        devices.size() != cache->devices.size() ||
        !std::equal(devices.begin(), devices.end(), cache->devices.begin(),
@@ -518,6 +543,10 @@ void MediaStreamManager::DevicesEnumerated(
     cache->valid = true;
     cache->devices = devices;
     need_update_clients = true;
+  } else {
+    // If stream_type is not a user type, there is no caching.  In such cases,
+    // we assume we always need to update the clients.
+    need_update_clients = (cache == NULL);
   }
 
   // Publish the result for all requests waiting for device list(s).
@@ -537,31 +566,44 @@ void MediaStreamManager::DevicesEnumerated(
   for (std::list<std::string>::iterator it = label_list.begin();
        it != label_list.end(); ++it) {
     DeviceRequest& request = requests_[*it];
+
+    // If one specific device has been requested, prune all other devices out.
+    StreamDeviceInfoArray tmp;
+    const StreamDeviceInfoArray* pruned_devices;
+    if (request.options.opt_device_id.empty()) {
+      pruned_devices = &devices;
+    } else {
+      for (StreamDeviceInfoArray::const_iterator device_it = devices.begin();
+           device_it != devices.end(); ++device_it) {
+        if (device_it->device_id == request.options.opt_device_id) {
+          tmp.push_back(*device_it);
+        }
+      }
+      pruned_devices = &tmp;
+    }
+
     switch (request.type) {
       case DeviceRequest::ENUMERATE_DEVICES:
         if (need_update_clients)
-          request.requester->DevicesEnumerated(*it, devices);
+          request.requester->DevicesEnumerated(*it, *pruned_devices);
         break;
       case DeviceRequest::OPEN_DEVICE:
-        for (StreamDeviceInfoArray::const_iterator device_it = devices.begin();
-             device_it != devices.end(); device_it++) {
-          if (request.requested_device_id == device_it->device_id) {
-            StreamDeviceInfo device = *device_it;
-            device.in_use = false;
-            device.session_id =
-                GetDeviceManager(device_it->stream_type)->Open(device);
-            request.state[device_it->stream_type] =
-                DeviceRequest::STATE_OPENING;
-            if (stream_type == content::MEDIA_STREAM_DEVICE_TYPE_AUDIO_CAPTURE)
-              request.audio_devices.push_back(device);
-            else
-              request.video_devices.push_back(device);
-            break;
-          }
+        if (!pruned_devices->empty()) {
+          StreamDeviceInfo device = pruned_devices->front();
+          // For OPEN_DEVICE requests, it is mandatory for the opt_device_id
+          // field to be provided.  See MediaStreamManager::OpenDevice().
+          DCHECK(!request.options.opt_device_id.empty());
+          DCHECK_EQ(request.options.opt_device_id, device.device_id);
+          device.in_use = false;
+          device.session_id =
+              GetDeviceManager(device.stream_type)->Open(device);
+          request.state[device.stream_type] = DeviceRequest::STATE_OPENING;
+          request.devices.push_back(device);
         }
         break;
       default:
-        device_settings_->AvailableDevices(*it, stream_type, devices);
+        device_settings_->AvailableDevices(*it, stream_type, *pruned_devices);
+        break;
     }
   }
   label_list.clear();
@@ -574,52 +616,58 @@ void MediaStreamManager::Error(MediaStreamType stream_type,
                                MediaStreamProviderError error) {
   // Find the device for the error call.
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
   for (DeviceRequests::iterator it = requests_.begin(); it != requests_.end();
        ++it) {
-    StreamDeviceInfoArray* devices = NULL;
-    if (stream_type == content::MEDIA_STREAM_DEVICE_TYPE_AUDIO_CAPTURE) {
-      devices = &(it->second.audio_devices);
-    } else if (stream_type == content::MEDIA_STREAM_DEVICE_TYPE_VIDEO_CAPTURE) {
-      devices = &(it->second.video_devices);
-    } else {
-      NOTREACHED();
-    }
+    StreamDeviceInfoArray& devices = it->second.devices;
 
-    int device_idx = 0;
-    for (StreamDeviceInfoArray::iterator device_it = devices->begin();
-         device_it != devices->end(); ++device_it, ++device_idx) {
-      if (device_it->session_id == capture_session_id) {
-        // We've found the failing device. Find the error case:
-        if (it->second.state[stream_type] == DeviceRequest::STATE_DONE) {
-          // 1. Already opened -> signal device failure and close device.
-          //    Use device_idx to signal which of the devices encountered an
-          //    error.
-          if (stream_type == content::MEDIA_STREAM_DEVICE_TYPE_AUDIO_CAPTURE) {
-            it->second.requester->AudioDeviceFailed(it->first, device_idx);
-          } else if (stream_type ==
-                     content::MEDIA_STREAM_DEVICE_TYPE_VIDEO_CAPTURE) {
-            it->second.requester->VideoDeviceFailed(it->first, device_idx);
-          }
-          GetDeviceManager(stream_type)->Close(capture_session_id);
-          // We don't erase the devices here so that we can update the UI
-          // properly in StopGeneratedStream().
-          it->second.state[stream_type] = DeviceRequest::STATE_ERROR;
+    int audio_device_idx = -1;
+    int video_device_idx = -1;
+    for (StreamDeviceInfoArray::iterator device_it = devices.begin();
+         device_it != devices.end(); ++device_it) {
+      if (content::IsAudioMediaType(device_it->stream_type)) {
+        ++audio_device_idx;
+      } else if (content::IsVideoMediaType(device_it->stream_type)) {
+        ++video_device_idx;
+      } else {
+        NOTREACHED();
+        continue;
+      }
+      if (device_it->stream_type != stream_type ||
+          device_it->session_id != capture_session_id) {
+        continue;
+      }
+      // We've found the failing device. Find the error case:
+      if (it->second.state[stream_type] == DeviceRequest::STATE_DONE) {
+        // 1. Already opened -> signal device failure and close device.
+        //    Use device_idx to signal which of the devices encountered an
+        //    error.
+        if (content::IsAudioMediaType(stream_type)) {
+          it->second.requester->AudioDeviceFailed(it->first, audio_device_idx);
+        } else if (content::IsVideoMediaType(stream_type)) {
+          it->second.requester->VideoDeviceFailed(it->first, video_device_idx);
         } else {
-          // Request is not done, devices are not opened in this case.
-          if ((it->second.audio_devices.size() +
-               it->second.video_devices.size()) <= 1) {
-            // 2. Device not opened and no other devices for this request ->
-            //    signal stream error and remove the request.
-            it->second.requester->StreamGenerationFailed(it->first);
-            requests_.erase(it);
-          } else {
-            // 3. Not opened but other devices exists for this request -> remove
-            //    device from list, but don't signal an error.
-            devices->erase(device_it);
-          }
+          NOTREACHED();
+          return;
+        }
+        GetDeviceManager(stream_type)->Close(capture_session_id);
+        // We don't erase the devices here so that we can update the UI
+        // properly in StopGeneratedStream().
+        it->second.state[stream_type] = DeviceRequest::STATE_ERROR;
+      } else {
+        // Request is not done, devices are not opened in this case.
+        if (devices.size() <= 1) {
+          // 2. Device not opened and no other devices for this request ->
+          //    signal stream error and remove the request.
+          it->second.requester->StreamGenerationFailed(it->first);
+          requests_.erase(it);
+        } else {
+          // 3. Not opened but other devices exists for this request -> remove
+          //    device from list, but don't signal an error.
+          devices.erase(device_it);  // NOTE: This invalidates device_it!
         }
-        return;
       }
+      return;
     }
   }
 }
@@ -628,53 +676,56 @@ void MediaStreamManager::DevicesAccepted(const std::string& label,
                                          const StreamDeviceInfoArray& devices) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   DeviceRequests::iterator request_it = requests_.find(label);
-  if (request_it != requests_.end()) {
-    if (devices.empty()) {
-      // No available devices or user didn't accept device usage.
-      request_it->second.requester->StreamGenerationFailed(request_it->first);
-      requests_.erase(request_it);
-      return;
-    }
+  if (request_it == requests_.end()) {
+    return;
+  }
 
-    // Loop through all device types for this request.
-    for (StreamDeviceInfoArray::const_iterator device_it = devices.begin();
-         device_it != devices.end(); ++device_it) {
-      StreamDeviceInfo device_info = *device_it;
-
-      // Set in_use to false to be able to track if this device has been
-      // opened. in_use might be true if the device type can be used in more
-      // than one session.
-      DCHECK_EQ(request_it->second.state[device_it->stream_type],
-                DeviceRequest::STATE_PENDING_APPROVAL);
-      device_info.in_use = false;
-      device_info.session_id =
-          GetDeviceManager(device_info.stream_type)->Open(device_info);
-      request_it->second.state[device_it->stream_type] =
-          DeviceRequest::STATE_OPENING;
-      if (device_info.stream_type ==
-          content::MEDIA_STREAM_DEVICE_TYPE_AUDIO_CAPTURE) {
-        request_it->second.audio_devices.push_back(device_info);
-      } else if (device_info.stream_type ==
-                 content::MEDIA_STREAM_DEVICE_TYPE_VIDEO_CAPTURE) {
-        request_it->second.video_devices.push_back(device_info);
-      } else {
-        NOTREACHED();
-      }
-    }
-    // Check if we received all stream types requested.
-    MediaStreamType stream_type =
-        content::MEDIA_STREAM_DEVICE_TYPE_AUDIO_CAPTURE;
-    if (Requested(request_it->second.options, stream_type) &&
-        request_it->second.audio_devices.size() == 0) {
-      request_it->second.state[stream_type] = DeviceRequest::STATE_ERROR;
-    }
-    stream_type = content::MEDIA_STREAM_DEVICE_TYPE_VIDEO_CAPTURE;
-    if (Requested(request_it->second.options, stream_type) &&
-        request_it->second.video_devices.size() == 0) {
-      request_it->second.state[stream_type] = DeviceRequest::STATE_ERROR;
-    }
+  DeviceRequest& request = request_it->second;
+
+  if (devices.empty()) {
+    // No available devices or user didn't accept device usage.
+    request.requester->StreamGenerationFailed(request_it->first);
+    requests_.erase(request_it);
     return;
   }
+
+  // Process all newly-accepted devices for this request.
+  for (StreamDeviceInfoArray::const_iterator device_it = devices.begin();
+       device_it != devices.end(); ++device_it) {
+    StreamDeviceInfo device_info = *device_it;  // make a copy
+
+    // Set in_use to false to be able to track if this device has been
+    // opened. in_use might be true if the device type can be used in more
+    // than one session.
+    DCHECK_EQ(request.state[device_it->stream_type],
+              DeviceRequest::STATE_PENDING_APPROVAL);
+    device_info.in_use = false;
+    device_info.session_id =
+        GetDeviceManager(device_info.stream_type)->Open(device_info);
+    request.state[device_it->stream_type] = DeviceRequest::STATE_OPENING;
+    request.devices.push_back(device_info);
+  }
+
+  // Check whether we've received all stream types requested.
+  bool found_audio = false, found_video = false;
+  for (StreamDeviceInfoArray::const_iterator i = request.devices.begin();
+       i != request.devices.end(); ++i) {
+    if (i->stream_type == request.options.audio_type) {
+      found_audio = true;
+    } else if (i->stream_type == request.options.video_type) {
+      found_video = true;
+    } else {
+      NOTREACHED();
+    }
+  }
+  if (request.options.audio_type != content::MEDIA_NO_SERVICE &&
+      !found_audio) {
+    request.state[request.options.audio_type] = DeviceRequest::STATE_ERROR;
+  }
+  if (request.options.video_type != content::MEDIA_NO_SERVICE &&
+      !found_video) {
+    request.state[request.options.video_type] = DeviceRequest::STATE_ERROR;
+  }
 }
 
 void MediaStreamManager::SettingsError(const std::string& label) {
@@ -689,9 +740,21 @@ void MediaStreamManager::SettingsError(const std::string& label) {
   }
 }
 
+void MediaStreamManager::SetAudioManager(media::AudioManager* audio_manager) {
+  LOG_IF(FATAL, (audio_manager_ != NULL) && (audio_manager_ != audio_manager))
+      << "Cannot override AudioManager after it has been set.";
+  audio_manager_ = audio_manager;
+}
+
 void MediaStreamManager::UseFakeDevice() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  video_capture_manager()->UseFakeDevice();
+  for (int i = content::MEDIA_NO_SERVICE + 1; i < content::NUM_MEDIA_TYPES;
+       ++i) {
+    const MediaStreamType stream_type = static_cast<MediaStreamType>(i);
+    if (content::IsVideoMediaType(stream_type)) {
+      GetVideoCaptureManager(stream_type)->UseFakeDevice();
+    }
+  }
   device_settings_->UseFakeUI();
 }
 
@@ -701,13 +764,20 @@ void MediaStreamManager::WillDestroyCurrentMessageLoop() {
   if (device_thread_.get()) {
     StopMonitoring();
 
-    video_capture_manager_->Unregister();
-    audio_input_device_manager_->Unregister();
+    for (int i = content::MEDIA_NO_SERVICE + 1; i < content::NUM_MEDIA_TYPES;
+         ++i) {
+      if (device_manager_[i]) {
+        device_manager_[i]->Unregister();
+      }
+    }
+
     device_thread_.reset();
   }
 
-  audio_input_device_manager_ = NULL;
-  video_capture_manager_ = NULL;
+  for (int i = content::MEDIA_NO_SERVICE + 1; i < content::NUM_MEDIA_TYPES;
+       ++i) {
+    device_manager_[i] = NULL;
+  }
   io_loop_ = NULL;
   device_settings_.reset();
 }
@@ -737,85 +807,86 @@ void MediaStreamManager::NotifyObserverDevicesClosed(DeviceRequest* request) {
 
 void MediaStreamManager::DevicesFromRequest(
     DeviceRequest* request, content::MediaStreamDevices* devices) {
-  StreamDeviceInfoArray::const_iterator it = request->audio_devices.begin();
-  for (; it != request->audio_devices.end(); ++it) {
-    devices->push_back(
-        content::MediaStreamDevice(
-            content::MEDIA_STREAM_DEVICE_TYPE_AUDIO_CAPTURE,
-            it->device_id,
-            it->name));
-  }
-  for (it = request->video_devices.begin(); it != request->video_devices.end();
-       ++it) {
-    devices->push_back(
-        content::MediaStreamDevice(
-            content::MEDIA_STREAM_DEVICE_TYPE_VIDEO_CAPTURE,
-            it->device_id,
-            it->name));
+  for (StreamDeviceInfoArray::const_iterator it = request->devices.begin();
+       it != request->devices.end(); ++it) {
+    devices->push_back(content::MediaStreamDevice(
+        it->stream_type, it->device_id, it->name));
   }
 }
 
 bool MediaStreamManager::RequestDone(const DeviceRequest& request) const {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  // Check if all devices are opened.
-  MediaStreamType stream_type = content::MEDIA_STREAM_DEVICE_TYPE_AUDIO_CAPTURE;
-  if (Requested(request.options, stream_type)) {
-    if (request.state[stream_type] != DeviceRequest::STATE_DONE &&
-        request.state[stream_type] != DeviceRequest::STATE_ERROR) {
-      return false;
-    }
 
-    for (StreamDeviceInfoArray::const_iterator it =
-         request.audio_devices.begin(); it != request.audio_devices.end();
-         ++it) {
-      if (it->in_use == false) {
-        return false;
-      }
-    }
+  const bool requested_audio =
+      content::IsAudioMediaType(request.options.audio_type);
+  const bool requested_video =
+      content::IsVideoMediaType(request.options.video_type);
+
+  const bool audio_done =
+      !requested_audio ||
+      request.state[request.options.audio_type] == DeviceRequest::STATE_DONE ||
+      request.state[request.options.audio_type] == DeviceRequest::STATE_ERROR;
+  if (!audio_done) {
+    return false;
   }
 
-  stream_type = content::MEDIA_STREAM_DEVICE_TYPE_VIDEO_CAPTURE;
-  if (Requested(request.options, stream_type)) {
-    if (request.state[stream_type] != DeviceRequest::STATE_DONE &&
-        request.state[stream_type] != DeviceRequest::STATE_ERROR) {
-      return false;
-    }
+  const bool video_done =
+      !requested_video ||
+      request.state[request.options.video_type] == DeviceRequest::STATE_DONE ||
+      request.state[request.options.video_type] == DeviceRequest::STATE_ERROR;
+  if (!video_done) {
+    return false;
+  }
 
-    for (StreamDeviceInfoArray::const_iterator it =
-         request.video_devices.begin(); it != request.video_devices.end();
-         ++it) {
-      if (it->in_use == false) {
-        return false;
-      }
+  for (StreamDeviceInfoArray::const_iterator it = request.devices.begin();
+       it != request.devices.end(); ++it) {
+    if ((!requested_audio && content::IsAudioMediaType(it->stream_type)) ||
+        (!requested_video && content::IsVideoMediaType(it->stream_type))) {
+      continue;
+    }
+    if (it->in_use == false) {
+      return false;
     }
   }
 
   return true;
 }
 
-// Called to get media capture device manager of specified type.
 MediaStreamProvider* MediaStreamManager::GetDeviceManager(
     MediaStreamType stream_type) {
-  if (stream_type == content::MEDIA_STREAM_DEVICE_TYPE_VIDEO_CAPTURE) {
-    return video_capture_manager();
-  } else if (stream_type == content::MEDIA_STREAM_DEVICE_TYPE_AUDIO_CAPTURE) {
-    return audio_input_device_manager();
-  }
-  NOTREACHED();
-  return NULL;
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  EnsureDeviceManagerStarted(stream_type);
+  return device_manager_[stream_type];
+}
+
+VideoCaptureManager* MediaStreamManager::GetVideoCaptureManager(
+    MediaStreamType stream_type) {
+  DCHECK(content::IsVideoMediaType(stream_type));
+  return reinterpret_cast<VideoCaptureManager*>(GetDeviceManager(stream_type));
+}
+
+AudioInputDeviceManager* MediaStreamManager::GetAudioInputDeviceManager(
+    MediaStreamType stream_type) {
+  DCHECK(content::IsAudioMediaType(stream_type));
+  return reinterpret_cast<AudioInputDeviceManager*>(
+      GetDeviceManager(stream_type));
 }
 
 void MediaStreamManager::OnDevicesChanged(
     base::SystemMonitor::DeviceType device_type) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  // NOTE: This method is only called in response to user audio/video device
+  // changes (from the operating system).
+
   MediaStreamType stream_type;
   EnumerationCache* cache;
   if (device_type == base::SystemMonitor::DEVTYPE_AUDIO_CAPTURE) {
-    stream_type = content::MEDIA_STREAM_DEVICE_TYPE_AUDIO_CAPTURE;
-    cache = &audio_enumeration_cache_;
+    stream_type = content::MEDIA_USER_AUDIO_CAPTURE;
+    cache = &user_audio_enumeration_cache_;
   } else if (device_type == base::SystemMonitor::DEVTYPE_VIDEO_CAPTURE) {
-    stream_type = content::MEDIA_STREAM_DEVICE_TYPE_VIDEO_CAPTURE;
-    cache = &video_enumeration_cache_;
+    stream_type = content::MEDIA_USER_VIDEO_CAPTURE;
+    cache = &user_video_enumeration_cache_;
   } else {
     return;  // Uninteresting device change.
   }