Refactor: Make MediaCaptureDevicesDispatcher have pluggable handlers.

chrome/browser/media/media_capture_devices_dispatcher.cc

Index: chrome/browser/media/media_capture_devices_dispatcher.cc
diff --git a/chrome/browser/media/media_capture_devices_dispatcher.cc b/chrome/browser/media/media_capture_devices_dispatcher.cc
index 79c93f5c1124def7b7aa119c90259682a0ae0532..b64a2c7ce6c9d7f0dbb63414b01feb1ceef63059 100644
--- a/chrome/browser/media/media_capture_devices_dispatcher.cc
+++ b/chrome/browser/media/media_capture_devices_dispatcher.cc
@@ -9,52 +9,38 @@
 #include "base/metrics/field_trial.h"
 #include "base/prefs/pref_service.h"
 #include "base/prefs/scoped_user_pref_update.h"
-#include "base/sha1.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/media/desktop_streams_registry.h"
+#include "chrome/browser/media/media_access_handler.h"
 #include "chrome/browser/media/media_stream_capture_indicator.h"
-#include "chrome/browser/media/media_stream_device_permissions.h"
-#include "chrome/browser/media/media_stream_infobar_delegate.h"
-#include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/media/permission_bubble_media_access_handler.h"
 #include "chrome/browser/ui/browser.h"
-#include "chrome/browser/ui/browser_finder.h"
 #include "chrome/browser/ui/browser_window.h"
-#include "chrome/browser/ui/screen_capture_notification_ui.h"
-#include "chrome/browser/ui/simple_message_box.h"
-#include "chrome/browser/ui/website_settings/permission_bubble_manager.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/chrome_version_info.h"
 #include "chrome/common/pref_names.h"
-#include "chrome/grit/generated_resources.h"
-#include "components/content_settings/core/browser/host_content_settings_map.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "content/public/browser/browser_thread.h"
-#include "content/public/browser/desktop_media_id.h"
 #include "content/public/browser/media_capture_devices.h"
-#include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_source.h"
-#include "content/public/browser/notification_types.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/media_stream_request.h"
 #include "extensions/common/constants.h"
-#include "media/audio/audio_manager_base.h"
 #include "media/base/media_switches.h"
 #include "net/base/net_util.h"
-#include "third_party/webrtc/modules/desktop_capture/desktop_capture_types.h"
-#include "ui/base/l10n/l10n_util.h"
 
 #if defined(OS_CHROMEOS)
 #include "ash/shell.h"
 #endif  // defined(OS_CHROMEOS)
 
 #if defined(ENABLE_EXTENSIONS)
-#include "chrome/browser/extensions/api/tab_capture/tab_capture_registry.h"
-#include "extensions/browser/app_window/app_window.h"
-#include "extensions/browser/app_window/app_window_registry.h"
+#include "chrome/browser/media/desktop_capture_access_handler.h"
+#include "chrome/browser/media/extension_media_access_handler.h"
+#include "chrome/browser/media/tab_capture_access_handler.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/common/extension.h"
 #include "extensions/common/permissions/permissions_data.h"
@@ -66,16 +52,6 @@ using content::MediaStreamDevices;
 
 namespace {
 
-// A finch experiment to enable the permission bubble for media requests only.
-bool MediaStreamPermissionBubbleExperimentEnabled() {
-  const std::string group =
-      base::FieldTrialList::FindFullName("MediaStreamPermissionBubble");
-  if (group == "enabled")
-    return true;
-
-  return false;
-}
-
 // Finds a device in |devices| that has |device_id|, or NULL if not found.
 const content::MediaStreamDevice* FindDeviceWithId(
     const content::MediaStreamDevices& devices,
@@ -90,161 +66,13 @@ const content::MediaStreamDevice* FindDeviceWithId(
 }
 
 #if defined(ENABLE_EXTENSIONS)
-// This is a short-term solution to grant camera and/or microphone access to
-// extensions:
-// 1. Virtual keyboard extension.
-// 2. Flutter gesture recognition extension.
-// 3. TODO(smus): Airbender experiment 1.
-// 4. TODO(smus): Airbender experiment 2.
-// 5. Hotwording component extension.
-// 6. XKB input method component extension.
-// 7. M17n/T13n/CJK input method component extension.
-// Once http://crbug.com/292856 is fixed, remove this whitelist.
-bool IsMediaRequestWhitelistedForExtension(
-    const extensions::Extension* extension) {
-  return extension->id() == "mppnpdlheglhdfmldimlhpnegondlapf" ||
-      extension->id() == "jokbpnebhdcladagohdnfgjcpejggllo" ||
-      extension->id() == "clffjmdilanldobdnedchkdbofoimcgb" ||
-      extension->id() == "nnckehldicaciogcbchegobnafnjkcne" ||
-      extension->id() == "nbpagnldghgfoolbancepceaanlmhfmd" ||
-      extension->id() == "jkghodnilhceideoidjikpgommlajknk" ||
-      extension->id() == "gjaehgfemfahhmlgpdfknkhdnemmolop";
-}
-
-bool IsBuiltInExtension(const GURL& origin) {
-  return
-      // Feedback Extension.
-      origin.spec() == "chrome-extension://gfdkimpbcpahaombhbimeihdjnejgicl/";
-}
-
-// Returns true of the security origin is associated with casting.
-bool IsOriginForCasting(const GURL& origin) {
-  // Whitelisted tab casting extensions.
-  return
-      // Dev
-      origin.spec() == "chrome-extension://enhhojjnijigcajfphajepfemndkmdlo/" ||
-      // Canary
-      origin.spec() == "chrome-extension://hfaagokkkhdbgiakmmlclaapfelnkoah/" ||
-      // Beta (internal)
-      origin.spec() == "chrome-extension://fmfcbgogabcbclcofgocippekhfcmgfj/" ||
-      // Google Cast Beta
-      origin.spec() == "chrome-extension://dliochdbjfkdbacpmhlcpmleaejidimm/" ||
-      // Google Cast Stable
-      origin.spec() == "chrome-extension://boadgeojelhgndaghljhdicfkmllpafd/" ||
-      // http://crbug.com/457908
-      origin.spec() == "chrome-extension://ekpaaapppgpmolpcldedioblbkmijaca/" ||
-      origin.spec() == "chrome-extension://fjhoaacokmgbjemoflkofnenfaiekifl/";
-}
-
-bool IsExtensionWhitelistedForScreenCapture(
-    const extensions::Extension* extension) {
-#if defined(OS_CHROMEOS)
-  std::string hash = base::SHA1HashString(extension->id());
-  std::string hex_hash = base::HexEncode(hash.c_str(), hash.length());
-
-  // crbug.com/446688
-  return hex_hash == "4F25792AF1AA7483936DE29C07806F203C7170A0" ||
-         hex_hash == "BD8781D757D830FC2E85470A1B6E8A718B7EE0D9" ||
-         hex_hash == "4AC2B6C63C6480D150DFDA13E4A5956EB1D0DDBB" ||
-         hex_hash == "81986D4F846CEDDDB962643FA501D1780DD441BB";
-#else
-  return false;
-#endif  // defined(OS_CHROMEOS)
-}
-#endif  // defined(ENABLE_EXTENSIONS)
-
-// Helper to get title of the calling application shown in the screen capture
-// notification.
-base::string16 GetApplicationTitle(content::WebContents* web_contents,
-                                   const extensions::Extension* extension) {
-  // Use extension name as title for extensions and host/origin for drive-by
-  // web.
-  std::string title;
-#if defined(ENABLE_EXTENSIONS)
-  if (extension) {
-    title = extension->name();
-    return base::UTF8ToUTF16(title);
-  }
-#endif
-  GURL url = web_contents->GetURL();
-  title = url.SchemeIsSecure() ? net::GetHostAndOptionalPort(url)
-                               : url.GetOrigin().spec();
-  return base::UTF8ToUTF16(title);
-}
-
-// Helper to get list of media stream devices for desktop capture in |devices|.
-// Registers to display notification if |display_notification| is true.
-// Returns an instance of MediaStreamUI to be passed to content layer.
-scoped_ptr<content::MediaStreamUI> GetDevicesForDesktopCapture(
-    content::MediaStreamDevices* devices,
-    content::DesktopMediaID media_id,
-    bool capture_audio,
-    bool display_notification,
-    const base::string16& application_title,
-    const base::string16& registered_extension_name) {
-  DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  scoped_ptr<content::MediaStreamUI> ui;
-
-  // Add selected desktop source to the list.
-  devices->push_back(content::MediaStreamDevice(
-      content::MEDIA_DESKTOP_VIDEO_CAPTURE, media_id.ToString(), "Screen"));
-  if (capture_audio) {
-    // Use the special loopback device ID for system audio capture.
-    devices->push_back(content::MediaStreamDevice(
-        content::MEDIA_DESKTOP_AUDIO_CAPTURE,
-        media::AudioManagerBase::kLoopbackInputDeviceId, "System Audio"));
-  }
-
-  // If required, register to display the notification for stream capture.
-  if (display_notification) {
-    if (application_title == registered_extension_name) {
-      ui = ScreenCaptureNotificationUI::Create(l10n_util::GetStringFUTF16(
-          IDS_MEDIA_SCREEN_CAPTURE_NOTIFICATION_TEXT,
-          application_title));
-    } else {
-      ui = ScreenCaptureNotificationUI::Create(l10n_util::GetStringFUTF16(
-          IDS_MEDIA_SCREEN_CAPTURE_NOTIFICATION_TEXT_DELEGATED,
-          registered_extension_name,
-          application_title));
-    }
-  }
-
-  return ui.Pass();
-}
-
-#if !defined(OS_ANDROID)
-// Find browser or app window from a given |web_contents|.
-gfx::NativeWindow FindParentWindowForWebContents(
-    content::WebContents* web_contents) {
-  Browser* browser = chrome::FindBrowserWithWebContents(web_contents);
-  if (browser && browser->window())
-    return browser->window()->GetNativeWindow();
-
-  const extensions::AppWindowRegistry::AppWindowList& window_list =
-      extensions::AppWindowRegistry::Get(
-          web_contents->GetBrowserContext())->app_windows();
-  for (extensions::AppWindowRegistry::AppWindowList::const_iterator iter =
-           window_list.begin();
-       iter != window_list.end(); ++iter) {
-    if ((*iter)->web_contents() == web_contents)
-      return (*iter)->GetNativeWindow();
-  }
-
-  return NULL;
+inline DesktopCaptureAccessHandler* ToDesktopCaptureAccessHandler(
+    MediaAccessHandler* handler) {
+  return static_cast<DesktopCaptureAccessHandler*>(handler);
 }
 #endif
-
 }  // namespace
 
-MediaCaptureDevicesDispatcher::PendingAccessRequest::PendingAccessRequest(
-    const content::MediaStreamRequest& request,
-    const content::MediaResponseCallback& callback)
-    : request(request),
-      callback(callback) {
-}
-
-MediaCaptureDevicesDispatcher::PendingAccessRequest::~PendingAccessRequest() {}
-
 MediaCaptureDevicesDispatcher* MediaCaptureDevicesDispatcher::GetInstance() {
   return Singleton<MediaCaptureDevicesDispatcher>::get();
 }
@@ -252,14 +80,7 @@ MediaCaptureDevicesDispatcher* MediaCaptureDevicesDispatcher::GetInstance() {
 MediaCaptureDevicesDispatcher::MediaCaptureDevicesDispatcher()
     : is_device_enumeration_disabled_(false),
       media_stream_capture_indicator_(new MediaStreamCaptureIndicator()) {
-  // MediaCaptureDevicesDispatcher is a singleton. It should be created on
-  // UI thread. Otherwise, it will not receive
-  // content::NOTIFICATION_WEB_CONTENTS_DESTROYED, and that will result in
-  // possible use after free.
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  notifications_registrar_.Add(
-      this, content::NOTIFICATION_WEB_CONTENTS_DESTROYED,
-      content::NotificationService::AllSources());
 
 #if defined(OS_MACOSX)
   // AVFoundation is used for video/audio device monitoring and video capture.
@@ -269,6 +90,13 @@ MediaCaptureDevicesDispatcher::MediaCaptureDevicesDispatcher()
         switches::kEnableAVFoundation);
   }
 #endif
+
+#if defined(ENABLE_EXTENSIONS)
+  media_access_handlers_.push_back(new ExtensionMediaAccessHandler());
+  media_access_handlers_.push_back(new DesktopCaptureAccessHandler());
+  media_access_handlers_.push_back(new TabCaptureAccessHandler());
+#endif
+  media_access_handlers_.push_back(new PermissionBubbleMediaAccessHandler());
 }
 
 MediaCaptureDevicesDispatcher::~MediaCaptureDevicesDispatcher() {}
@@ -281,6 +109,24 @@ void MediaCaptureDevicesDispatcher::RegisterProfilePrefs(
                                std::string());
 }
 
+bool MediaCaptureDevicesDispatcher::IsOriginForCasting(const GURL& origin) {
+  // Whitelisted tab casting extensions.
+  return
+      // Dev
+      origin.spec() == "chrome-extension://enhhojjnijigcajfphajepfemndkmdlo/" ||
+      // Canary
+      origin.spec() == "chrome-extension://hfaagokkkhdbgiakmmlclaapfelnkoah/" ||
+      // Beta (internal)
+      origin.spec() == "chrome-extension://fmfcbgogabcbclcofgocippekhfcmgfj/" ||
+      // Google Cast Beta
+      origin.spec() == "chrome-extension://dliochdbjfkdbacpmhlcpmleaejidimm/" ||
+      // Google Cast Stable
+      origin.spec() == "chrome-extension://boadgeojelhgndaghljhdicfkmllpafd/" ||
+      // http://crbug.com/457908
+      origin.spec() == "chrome-extension://ekpaaapppgpmolpcldedioblbkmijaca/" ||
+      origin.spec() == "chrome-extension://fjhoaacokmgbjemoflkofnenfaiekifl/";
+}
+
 void MediaCaptureDevicesDispatcher::AddObserver(Observer* observer) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   if (!observers_.HasObserver(observer))
@@ -310,18 +156,6 @@ MediaCaptureDevicesDispatcher::GetVideoCaptureDevices() {
   return MediaCaptureDevices::GetInstance()->GetVideoCaptureDevices();
 }
 
-void MediaCaptureDevicesDispatcher::Observe(
-    int type,
-    const content::NotificationSource& source,
-    const content::NotificationDetails& details) {
-  DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  if (type == content::NOTIFICATION_WEB_CONTENTS_DESTROYED) {
-    content::WebContents* web_contents =
-        content::Source<content::WebContents>(source).ptr();
-    pending_requests_.erase(web_contents);
-  }
-}
-
 void MediaCaptureDevicesDispatcher::ProcessMediaAccessRequest(
     content::WebContents* web_contents,
     const content::MediaStreamRequest& request,
@@ -329,28 +163,15 @@ void MediaCaptureDevicesDispatcher::ProcessMediaAccessRequest(
     const extensions::Extension* extension) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
-  if (request.video_type == content::MEDIA_DESKTOP_VIDEO_CAPTURE ||
-      request.audio_type == content::MEDIA_DESKTOP_AUDIO_CAPTURE) {
-    ProcessDesktopCaptureAccessRequest(
-        web_contents, request, callback, extension);
-  } else if (request.video_type == content::MEDIA_TAB_VIDEO_CAPTURE ||
-             request.audio_type == content::MEDIA_TAB_AUDIO_CAPTURE) {
-    ProcessTabCaptureAccessRequest(
-        web_contents, request, callback, extension);
-  } else {
-#if defined(ENABLE_EXTENSIONS)
-    bool is_whitelisted =
-        extension && (extension->is_platform_app() ||
-                      IsMediaRequestWhitelistedForExtension(extension));
-    if (is_whitelisted) {
-      // For extensions access is approved based on extension permissions.
-      ProcessMediaAccessRequestFromPlatformAppOrExtension(
-          web_contents, request, callback, extension);
+  for (MediaAccessHandler* handler : media_access_handlers_) {
+    if (handler->SupportsStreamType(request.video_type, extension) ||
+        handler->SupportsStreamType(request.audio_type, extension)) {
+      handler->HandleRequest(web_contents, request, callback, extension);
       return;
     }
-#endif
-    ProcessRegularMediaAccessRequest(web_contents, request, callback);
   }
+  callback.Run(content::MediaStreamDevices(),
+               content::MEDIA_DEVICE_NOT_SUPPORTED, nullptr);
 }
 
 bool MediaCaptureDevicesDispatcher::CheckMediaAccessPermission(
@@ -358,487 +179,23 @@ bool MediaCaptureDevicesDispatcher::CheckMediaAccessPermission(
     const GURL& security_origin,
     content::MediaStreamType type) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  DCHECK(type == content::MEDIA_DEVICE_AUDIO_CAPTURE ||
-         type == content::MEDIA_DEVICE_VIDEO_CAPTURE);
-
-  Profile* profile =
-      Profile::FromBrowserContext(web_contents->GetBrowserContext());
-
-  ContentSettingsType contentSettingsType =
-      type == content::MEDIA_DEVICE_AUDIO_CAPTURE
-          ? CONTENT_SETTINGS_TYPE_MEDIASTREAM_MIC
-          : CONTENT_SETTINGS_TYPE_MEDIASTREAM_CAMERA;
-
-  if (CheckAllowAllMediaStreamContentForOrigin(
-          profile, security_origin, contentSettingsType)) {
-    return true;
-  }
-
-  const char* policy_name = type == content::MEDIA_DEVICE_AUDIO_CAPTURE
-                                ? prefs::kAudioCaptureAllowed
-                                : prefs::kVideoCaptureAllowed;
-  const char* list_policy_name = type == content::MEDIA_DEVICE_AUDIO_CAPTURE
-                                     ? prefs::kAudioCaptureAllowedUrls
-                                     : prefs::kVideoCaptureAllowedUrls;
-  if (GetDevicePolicy(
-          profile, security_origin, policy_name, list_policy_name) ==
-      ALWAYS_ALLOW) {
-    return true;
-  }
-
-  // There's no secondary URL for these content types, hence duplicating
-  // |security_origin|.
-  if (profile->GetHostContentSettingsMap()->GetContentSetting(
-          security_origin,
-          security_origin,
-          contentSettingsType,
-          content_settings::ResourceIdentifier()) == CONTENT_SETTING_ALLOW) {
-    return true;
-  }
-
-  return false;
+  return CheckMediaAccessPermission(web_contents, security_origin, type,
+                                    nullptr);
 }
 
-#if defined(ENABLE_EXTENSIONS)
 bool MediaCaptureDevicesDispatcher::CheckMediaAccessPermission(
     content::WebContents* web_contents,
     const GURL& security_origin,
     content::MediaStreamType type,
     const extensions::Extension* extension) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  DCHECK(type == content::MEDIA_DEVICE_AUDIO_CAPTURE ||
-         type == content::MEDIA_DEVICE_VIDEO_CAPTURE);
-
-  if (extension->is_platform_app() ||
-      IsMediaRequestWhitelistedForExtension(extension)) {
-    return extension->permissions_data()->HasAPIPermission(
-        type == content::MEDIA_DEVICE_AUDIO_CAPTURE
-            ? extensions::APIPermission::kAudioCapture
-            : extensions::APIPermission::kVideoCapture);
-  }
-
-  return CheckMediaAccessPermission(web_contents, security_origin, type);
-}
-#endif
-
-void MediaCaptureDevicesDispatcher::ProcessDesktopCaptureAccessRequest(
-    content::WebContents* web_contents,
-    const content::MediaStreamRequest& request,
-    const content::MediaResponseCallback& callback,
-    const extensions::Extension* extension) {
-  content::MediaStreamDevices devices;
-  scoped_ptr<content::MediaStreamUI> ui;
-
-  if (request.video_type != content::MEDIA_DESKTOP_VIDEO_CAPTURE) {
-    callback.Run(devices, content::MEDIA_DEVICE_INVALID_STATE, ui.Pass());
-    return;
-  }
-
-  // If the device id wasn't specified then this is a screen capture request
-  // (i.e. chooseDesktopMedia() API wasn't used to generate device id).
-  if (request.requested_video_device_id.empty()) {
-    ProcessScreenCaptureAccessRequest(
-        web_contents, request, callback, extension);
-    return;
-  }
-
-  // The extension name that the stream is registered with.
-  std::string original_extension_name;
-  // Resolve DesktopMediaID for the specified device id.
-  content::DesktopMediaID media_id;
-  // TODO(miu): Replace "main RenderFrame" IDs with the request's actual
-  // RenderFrame IDs once the desktop capture extension API implementation is
-  // fixed.  http://crbug.com/304341
-  content::WebContents* const web_contents_for_stream =
-      content::WebContents::FromRenderFrameHost(
-          content::RenderFrameHost::FromID(request.render_process_id,
-                                           request.render_frame_id));
-  content::RenderFrameHost* const main_frame = web_contents_for_stream ?
-      web_contents_for_stream->GetMainFrame() : NULL;
-  if (main_frame) {
-    media_id = GetDesktopStreamsRegistry()->RequestMediaForStreamId(
-        request.requested_video_device_id,
-        main_frame->GetProcess()->GetID(),
-        main_frame->GetRoutingID(),
-        request.security_origin,
-        &original_extension_name);
-  }
-
-  // Received invalid device id.
-  if (media_id.type == content::DesktopMediaID::TYPE_NONE) {
-    callback.Run(devices, content::MEDIA_DEVICE_INVALID_STATE, ui.Pass());
-    return;
-  }
-
-  bool loopback_audio_supported = false;
-#if defined(USE_CRAS) || defined(OS_WIN)
-  // Currently loopback audio capture is supported only on Windows and ChromeOS.
-  loopback_audio_supported = true;
-#endif
-
-  // Audio is only supported for screen capture streams.
-  bool capture_audio =
-      (media_id.type == content::DesktopMediaID::TYPE_SCREEN &&
-       request.audio_type == content::MEDIA_DESKTOP_AUDIO_CAPTURE &&
-       loopback_audio_supported);
-
-  ui = GetDevicesForDesktopCapture(
-      &devices, media_id, capture_audio, true,
-      GetApplicationTitle(web_contents, extension),
-      base::UTF8ToUTF16(original_extension_name));
-
-  callback.Run(devices, content::MEDIA_DEVICE_OK, ui.Pass());
-}
-
-void MediaCaptureDevicesDispatcher::ProcessScreenCaptureAccessRequest(
-    content::WebContents* web_contents,
-    const content::MediaStreamRequest& request,
-    const content::MediaResponseCallback& callback,
-    const extensions::Extension* extension) {
-  content::MediaStreamDevices devices;
-  scoped_ptr<content::MediaStreamUI> ui;
-
-  DCHECK_EQ(request.video_type, content::MEDIA_DESKTOP_VIDEO_CAPTURE);
-
-  bool loopback_audio_supported = false;
-#if defined(USE_CRAS) || defined(OS_WIN)
-  // Currently loopback audio capture is supported only on Windows and ChromeOS.
-  loopback_audio_supported = true;
-#endif
-
-  bool component_extension = false;
-#if defined(ENABLE_EXTENSIONS)
-  component_extension =
-      extension && extension->location() == extensions::Manifest::COMPONENT;
-#endif
-
-  bool screen_capture_enabled =
-      base::CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kEnableUserMediaScreenCapturing);
-#if defined(ENABLE_EXTENSIONS)
-  screen_capture_enabled |=
-      IsOriginForCasting(request.security_origin) ||
-      IsExtensionWhitelistedForScreenCapture(extension) ||
-      IsBuiltInExtension(request.security_origin);
-#endif
-
-  const bool origin_is_secure =
-      request.security_origin.SchemeIsSecure() ||
-      request.security_origin.SchemeIs(extensions::kExtensionScheme) ||
-      base::CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kAllowHttpScreenCapture);
-
-  // If basic conditions (screen capturing is enabled and origin is secure)
-  // aren't fulfilled, we'll use "invalid state" as result. Otherwise, we set
-  // it after checking permission.
-  // TODO(grunell): It would be good to change this result for something else,
-  // probably a new one.
-  content::MediaStreamRequestResult result =
-      content::MEDIA_DEVICE_INVALID_STATE;
-
-  // Approve request only when the following conditions are met:
-  //  1. Screen capturing is enabled via command line switch or white-listed for
-  //     the given origin.
-  //  2. Request comes from a page with a secure origin or from an extension.
-  if (screen_capture_enabled && origin_is_secure) {
-    // Get title of the calling application prior to showing the message box.
-    // chrome::ShowMessageBox() starts a nested message loop which may allow
-    // |web_contents| to be destroyed on the UI thread before the message box
-    // is closed. See http://crbug.com/326690.
-    base::string16 application_title =
-        GetApplicationTitle(web_contents, extension);
-#if !defined(OS_ANDROID)
-    gfx::NativeWindow parent_window =
-        FindParentWindowForWebContents(web_contents);
-#else
-    gfx::NativeWindow parent_window = NULL;
-#endif
-    web_contents = NULL;
-
-    bool whitelisted_extension = false;
-#if defined(ENABLE_EXTENSIONS)
-    whitelisted_extension = IsExtensionWhitelistedForScreenCapture(
-        extension);
-#endif
-
-    // For whitelisted or component extensions, bypass message box.
-    bool user_approved = false;
-    if (!whitelisted_extension && !component_extension) {
-      base::string16 application_name =
-          base::UTF8ToUTF16(request.security_origin.spec());
-#if defined(ENABLE_EXTENSIONS)
-      if (extension)
-        application_name = base::UTF8ToUTF16(extension->name());
-#endif
-      base::string16 confirmation_text = l10n_util::GetStringFUTF16(
-          request.audio_type == content::MEDIA_NO_SERVICE ?
-              IDS_MEDIA_SCREEN_CAPTURE_CONFIRMATION_TEXT :
-              IDS_MEDIA_SCREEN_AND_AUDIO_CAPTURE_CONFIRMATION_TEXT,
-          application_name);
-      chrome::MessageBoxResult result = chrome::ShowMessageBox(
-          parent_window,
-          l10n_util::GetStringFUTF16(
-              IDS_MEDIA_SCREEN_CAPTURE_CONFIRMATION_TITLE, application_name),
-          confirmation_text,
-          chrome::MESSAGE_BOX_TYPE_QUESTION);
-      user_approved = (result == chrome::MESSAGE_BOX_RESULT_YES);
-    }
-
-    if (user_approved || component_extension || whitelisted_extension) {
-      content::DesktopMediaID screen_id;
-#if defined(OS_CHROMEOS)
-      screen_id = content::DesktopMediaID::RegisterAuraWindow(
-          ash::Shell::GetInstance()->GetPrimaryRootWindow());
-#else  // defined(OS_CHROMEOS)
-      screen_id =
-          content::DesktopMediaID(content::DesktopMediaID::TYPE_SCREEN,
-                                  webrtc::kFullDesktopScreenId);
-#endif  // !defined(OS_CHROMEOS)
-
-      bool capture_audio =
-          (request.audio_type == content::MEDIA_DESKTOP_AUDIO_CAPTURE &&
-           loopback_audio_supported);
-
-      // Unless we're being invoked from a component extension, register to
-      // display the notification for stream capture.
-      bool display_notification = !component_extension;
-
-      ui = GetDevicesForDesktopCapture(&devices, screen_id, capture_audio,
-                                       display_notification, application_title,
-                                       application_title);
-      DCHECK(!devices.empty());
-    }
-
-    // The only case when devices can be empty is if the user has denied
-    // permission.
-    result = devices.empty() ? content::MEDIA_DEVICE_PERMISSION_DENIED
-                             : content::MEDIA_DEVICE_OK;
-  }
-
-  callback.Run(devices, result, ui.Pass());
-}
-
-void MediaCaptureDevicesDispatcher::ProcessTabCaptureAccessRequest(
-    content::WebContents* web_contents,
-    const content::MediaStreamRequest& request,
-    const content::MediaResponseCallback& callback,
-    const extensions::Extension* extension) {
-  content::MediaStreamDevices devices;
-  scoped_ptr<content::MediaStreamUI> ui;
-
-#if defined(ENABLE_EXTENSIONS)
-  Profile* profile =
-      Profile::FromBrowserContext(web_contents->GetBrowserContext());
-  extensions::TabCaptureRegistry* tab_capture_registry =
-      extensions::TabCaptureRegistry::Get(profile);
-  if (!tab_capture_registry) {
-    NOTREACHED();
-    callback.Run(devices, content::MEDIA_DEVICE_INVALID_STATE, ui.Pass());
-    return;
-  }
-  const bool tab_capture_allowed = tab_capture_registry->VerifyRequest(
-      request.render_process_id, request.render_frame_id, extension->id());
-
-  if (request.audio_type == content::MEDIA_TAB_AUDIO_CAPTURE &&
-      tab_capture_allowed &&
-      extension->permissions_data()->HasAPIPermission(
-          extensions::APIPermission::kTabCapture)) {
-    devices.push_back(content::MediaStreamDevice(
-        content::MEDIA_TAB_AUDIO_CAPTURE, std::string(), std::string()));
-  }
-
-  if (request.video_type == content::MEDIA_TAB_VIDEO_CAPTURE &&
-      tab_capture_allowed &&
-      extension->permissions_data()->HasAPIPermission(
-          extensions::APIPermission::kTabCapture)) {
-    devices.push_back(content::MediaStreamDevice(
-        content::MEDIA_TAB_VIDEO_CAPTURE, std::string(), std::string()));
-  }
-
-  if (!devices.empty()) {
-    ui = media_stream_capture_indicator_->RegisterMediaStream(
-        web_contents, devices);
-  }
-  callback.Run(
-    devices,
-    devices.empty() ? content::MEDIA_DEVICE_INVALID_STATE :
-                      content::MEDIA_DEVICE_OK,
-    ui.Pass());
-#else  // defined(ENABLE_EXTENSIONS)
-  callback.Run(devices, content::MEDIA_DEVICE_TAB_CAPTURE_FAILURE, ui.Pass());
-#endif  // defined(ENABLE_EXTENSIONS)
-}
-
-#if defined(ENABLE_EXTENSIONS)
-void MediaCaptureDevicesDispatcher::
-    ProcessMediaAccessRequestFromPlatformAppOrExtension(
-        content::WebContents* web_contents,
-        const content::MediaStreamRequest& request,
-        const content::MediaResponseCallback& callback,
-        const extensions::Extension* extension) {
-  // TODO(vrk): This code is largely duplicated in
-  // MediaStreamDevicesController::Accept(). Move this code into a shared method
-  // between the two classes.
-
-  Profile* profile =
-      Profile::FromBrowserContext(web_contents->GetBrowserContext());
-
-  bool audio_allowed =
-      request.audio_type == content::MEDIA_DEVICE_AUDIO_CAPTURE &&
-      extension->permissions_data()->HasAPIPermission(
-          extensions::APIPermission::kAudioCapture) &&
-      GetDevicePolicy(profile, extension->url(),
-                      prefs::kAudioCaptureAllowed,
-                      prefs::kAudioCaptureAllowedUrls) != ALWAYS_DENY;
-  bool video_allowed =
-      request.video_type == content::MEDIA_DEVICE_VIDEO_CAPTURE &&
-      extension->permissions_data()->HasAPIPermission(
-          extensions::APIPermission::kVideoCapture) &&
-      GetDevicePolicy(profile, extension->url(),
-                      prefs::kVideoCaptureAllowed,
-                      prefs::kVideoCaptureAllowedUrls) != ALWAYS_DENY;
-
-  bool get_default_audio_device = audio_allowed;
-  bool get_default_video_device = video_allowed;
-
-  content::MediaStreamDevices devices;
-
-  // Set an initial error result. If neither audio or video is allowed, we'll
-  // never try to get any device below but will just create |ui| and return an
-  // empty list with "invalid state" result. If at least one is allowed, we'll
-  // try to get device(s), and if failure, we want to return "no hardware"
-  // result.
-  // TODO(grunell): The invalid state result should be changed to a new denied
-  // result + a dcheck to ensure at least one of audio or video types is
-  // capture.
-  content::MediaStreamRequestResult result =
-      (audio_allowed || video_allowed) ? content::MEDIA_DEVICE_NO_HARDWARE
-                                       : content::MEDIA_DEVICE_INVALID_STATE;
-
-  // Get the exact audio or video device if an id is specified.
-  // We only set any error result here and before running the callback change
-  // it to OK if we have any device.
-  if (audio_allowed && !request.requested_audio_device_id.empty()) {
-    const content::MediaStreamDevice* audio_device =
-        GetRequestedAudioDevice(request.requested_audio_device_id);
-    if (audio_device) {
-      devices.push_back(*audio_device);
-      get_default_audio_device = false;
+  for (MediaAccessHandler* handler : media_access_handlers_) {
+    if (handler->SupportsStreamType(type, extension)) {
+      return handler->CheckMediaAccessPermission(web_contents, security_origin,
+                                                 type, extension);
     }
   }
-  if (video_allowed && !request.requested_video_device_id.empty()) {
-    const content::MediaStreamDevice* video_device =
-        GetRequestedVideoDevice(request.requested_video_device_id);
-    if (video_device) {
-      devices.push_back(*video_device);
-      get_default_video_device = false;
-    }
-  }
-
-  // If either or both audio and video devices were requested but not
-  // specified by id, get the default devices.
-  if (get_default_audio_device || get_default_video_device) {
-    GetDefaultDevicesForProfile(profile,
-                                get_default_audio_device,
-                                get_default_video_device,
-                                &devices);
-  }
-
-  scoped_ptr<content::MediaStreamUI> ui;
-  if (!devices.empty()) {
-    result = content::MEDIA_DEVICE_OK;
-    ui = media_stream_capture_indicator_->RegisterMediaStream(
-        web_contents, devices);
-  }
-
-  callback.Run(devices, result, ui.Pass());
-}
-#endif
-
-void MediaCaptureDevicesDispatcher::ProcessRegularMediaAccessRequest(
-    content::WebContents* web_contents,
-    const content::MediaStreamRequest& request,
-    const content::MediaResponseCallback& callback) {
-  DCHECK_CURRENTLY_ON(BrowserThread::UI);
-
-  RequestsQueue& queue = pending_requests_[web_contents];
-  queue.push_back(PendingAccessRequest(request, callback));
-
-  // If this is the only request then show the infobar.
-  if (queue.size() == 1)
-    ProcessQueuedAccessRequest(web_contents);
-}
-
-void MediaCaptureDevicesDispatcher::ProcessQueuedAccessRequest(
-    content::WebContents* web_contents) {
-  DCHECK_CURRENTLY_ON(BrowserThread::UI);
-
-  std::map<content::WebContents*, RequestsQueue>::iterator it =
-      pending_requests_.find(web_contents);
-
-  if (it == pending_requests_.end() || it->second.empty()) {
-    // Don't do anything if the tab was closed.
-    return;
-  }
-
-  DCHECK(!it->second.empty());
-
-  if (PermissionBubbleManager::Enabled() ||
-      MediaStreamPermissionBubbleExperimentEnabled()) {
-    scoped_ptr<MediaStreamDevicesController> controller(
-        new MediaStreamDevicesController(web_contents,
-            it->second.front().request,
-            base::Bind(&MediaCaptureDevicesDispatcher::OnAccessRequestResponse,
-                       base::Unretained(this), web_contents)));
-    if (controller->DismissInfoBarAndTakeActionOnSettings())
-      return;
-    PermissionBubbleManager* bubble_manager =
-        PermissionBubbleManager::FromWebContents(web_contents);
-    if (bubble_manager)
-      bubble_manager->AddRequest(controller.release());
-    return;
-  }
-
-  // TODO(gbillock): delete this block and the MediaStreamInfoBarDelegate
-  // when we've transitioned to bubbles. (crbug/337458)
-  MediaStreamInfoBarDelegate::Create(
-      web_contents, it->second.front().request,
-      base::Bind(&MediaCaptureDevicesDispatcher::OnAccessRequestResponse,
-                 base::Unretained(this), web_contents));
-}
-
-void MediaCaptureDevicesDispatcher::OnAccessRequestResponse(
-    content::WebContents* web_contents,
-    const content::MediaStreamDevices& devices,
-    content::MediaStreamRequestResult result,
-    scoped_ptr<content::MediaStreamUI> ui) {
-  DCHECK_CURRENTLY_ON(BrowserThread::UI);
-
-  std::map<content::WebContents*, RequestsQueue>::iterator it =
-      pending_requests_.find(web_contents);
-  if (it == pending_requests_.end()) {
-    // WebContents has been destroyed. Don't need to do anything.
-    return;
-  }
-
-  RequestsQueue& queue(it->second);
-  if (queue.empty())
-    return;
-
-  content::MediaResponseCallback callback = queue.front().callback;
-  queue.pop_front();
-
-  if (!queue.empty()) {
-    // Post a task to process next queued request. It has to be done
-    // asynchronously to make sure that calling infobar is not destroyed until
-    // after this function returns.
-    BrowserThread::PostTask(
-        BrowserThread::UI, FROM_HERE,
-        base::Bind(&MediaCaptureDevicesDispatcher::ProcessQueuedAccessRequest,
-                   base::Unretained(this), web_contents));
-  }
-
-  callback.Run(devices, result, ui.Pass());
+  return false;
 }
 
 void MediaCaptureDevicesDispatcher::GetDefaultDevicesForProfile(
@@ -990,47 +347,11 @@ void MediaCaptureDevicesDispatcher::UpdateMediaRequestStateOnUIThread(
     const GURL& security_origin,
     content::MediaStreamType stream_type,
     content::MediaRequestState state) {
-  // Track desktop capture sessions.  Tracking is necessary to avoid unbalanced
-  // session counts since not all requests will reach MEDIA_REQUEST_STATE_DONE,
-  // but they will all reach MEDIA_REQUEST_STATE_CLOSING.
-  if (stream_type == content::MEDIA_DESKTOP_VIDEO_CAPTURE) {
-    if (state == content::MEDIA_REQUEST_STATE_DONE) {
-      DesktopCaptureSession session = { render_process_id, render_frame_id,
-                                        page_request_id };
-      desktop_capture_sessions_.push_back(session);
-    } else if (state == content::MEDIA_REQUEST_STATE_CLOSING) {
-      for (DesktopCaptureSessions::iterator it =
-               desktop_capture_sessions_.begin();
-           it != desktop_capture_sessions_.end();
-           ++it) {
-        if (it->render_process_id == render_process_id &&
-            it->render_frame_id == render_frame_id &&
-            it->page_request_id == page_request_id) {
-          desktop_capture_sessions_.erase(it);
-          break;
-        }
-      }
-    }
-  }
-
-  // Cancel the request.
-  if (state == content::MEDIA_REQUEST_STATE_CLOSING) {
-    bool found = false;
-    for (RequestsQueues::iterator rqs_it = pending_requests_.begin();
-         rqs_it != pending_requests_.end(); ++rqs_it) {
-      RequestsQueue& queue = rqs_it->second;
-      for (RequestsQueue::iterator it = queue.begin();
-           it != queue.end(); ++it) {
-        if (it->request.render_process_id == render_process_id &&
-            it->request.render_frame_id == render_frame_id &&
-            it->request.page_request_id == page_request_id) {
-          queue.erase(it);
-          found = true;
-          break;
-        }
-      }
-      if (found)
-        break;
+  for (MediaAccessHandler* handler : media_access_handlers_) {
+    if (handler->SupportsStreamType(stream_type, nullptr)) {
+      handler->UpdateMediaRequestState(render_process_id, render_frame_id,
+                                       page_request_id, stream_type, state);
+      break;
     }
   }
 
@@ -1062,7 +383,15 @@ void MediaCaptureDevicesDispatcher::OnCreatingAudioStreamOnUIThread(
 
 bool MediaCaptureDevicesDispatcher::IsDesktopCaptureInProgress() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  return desktop_capture_sessions_.size() > 0;
+#if defined(ENABLE_EXTENSIONS)
+  for (MediaAccessHandler* handler : media_access_handlers_) {
+    if (handler->SupportsStreamType(content::MEDIA_DESKTOP_VIDEO_CAPTURE,
+                                    NULL)) {
+      return ToDesktopCaptureAccessHandler(handler)->IsCaptureInProgress();
+    }
+  }
+#endif
+  return false;
 }
 
 void MediaCaptureDevicesDispatcher::SetTestAudioCaptureDevices(