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

content/browser/renderer_host/media/audio_input_renderer_host.cc

Index: content/browser/renderer_host/media/audio_input_renderer_host.cc
diff --git a/content/browser/renderer_host/media/audio_input_renderer_host.cc b/content/browser/renderer_host/media/audio_input_renderer_host.cc
index 5c7380f1c157faf4f3c3e31d7dfd8c87c68a767b..e810dfcfbd224ad5684c53380403bdb3daf9645d 100644
--- a/content/browser/renderer_host/media/audio_input_renderer_host.cc
+++ b/content/browser/renderer_host/media/audio_input_renderer_host.cc
@@ -12,6 +12,7 @@
 #include "content/browser/renderer_host/media/audio_input_sync_writer.h"
 #include "content/browser/renderer_host/media/media_stream_manager.h"
 #include "content/common/media/audio_messages.h"
+#include "content/public/common/media_stream_request.h"
 
 using content::BrowserMessageFilter;
 using content::BrowserThread;
@@ -180,7 +181,12 @@ void AudioInputRendererHost::OnStartDevice(int stream_id, int session_id) {
 
   // Start the device with the session_id. If the device is started
   // successfully, OnDeviceStarted() callback will be triggered.
-  media_stream_manager_->audio_input_device_manager()->Start(session_id, this);
+  media_stream_manager_->GetAudioInputDeviceManager(
+      content::MEDIA_DEVICE_AUDIO_CAPTURE)->Start(session_id, this);
+  // NOTE: Currently, use of AudioInputHostMsg_* only applies to the
+  // MEDIA_DEVICE_AUDIO_CAPTURE.  The IPC interface could theoretically be
+  // extended to allow operation with the other video capture types (e.g., tab
+  // mirroring).
 }
 
 void AudioInputRendererHost::OnCreateStream(
@@ -337,7 +343,8 @@ void AudioInputRendererHost::OnDeviceStopped(int session_id) {
 void AudioInputRendererHost::StopAndDeleteDevice(int session_id) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
-  media_stream_manager_->audio_input_device_manager()->Stop(session_id);
+  media_stream_manager_->GetAudioInputDeviceManager(
+      content::MEDIA_DEVICE_AUDIO_CAPTURE)->Stop(session_id);
 
   // Delete the session entry.
   session_entries_.erase(session_id);