Makes it possible to run content_browsertests with --as-browser and fake WebRTC devices.

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..605cc7a546fff01bd4137f87e04150e5cec8f39f 100644
--- a/content/browser/renderer_host/media/media_stream_manager.cc
+++ b/content/browser/renderer_host/media/media_stream_manager.cc
@@ -690,7 +690,14 @@ void MediaStreamManager::SettingsError(const std::string& label) {
 }
 
 void MediaStreamManager::UseFakeDevice() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  if(!BrowserThread::CurrentlyOn(BrowserThread::IO)) {
+    BrowserThread::PostTask(BrowserThread::IO,
+        FROM_HERE,
+        base::Bind(&media_stream::MediaStreamManager::UseFakeDevice,
+                   base::Unretained(this)));
+    return;
+  }
+
   video_capture_manager()->UseFakeDevice();
   device_settings_->UseFakeUI();
 }
@@ -715,6 +722,9 @@ void MediaStreamManager::WillDestroyCurrentMessageLoop() {
 void MediaStreamManager::NotifyObserverDevicesOpened(DeviceRequest* request) {
   content::MediaObserver* media_observer =
       content::GetContentClient()->browser()->GetMediaObserver();
+  // Check if the embedder isn't interested in the notification.

[jam, 2012/09/04 15:18:14]

nit: no need to comment this, per the style guide (i.e. no need to comment
something when it's obvious by looking at the code)

[phoglund_chromium, 2012/09/05 11:43:54]

Done.

+  if (media_observer == NULL)
+    return;
   content::MediaStreamDevices opened_devices;
   DevicesFromRequest(request, &opened_devices);
   DCHECK(!opened_devices.empty());
@@ -726,6 +736,9 @@ void MediaStreamManager::NotifyObserverDevicesOpened(DeviceRequest* request) {
 void MediaStreamManager::NotifyObserverDevicesClosed(DeviceRequest* request) {
   content::MediaObserver* media_observer =
       content::GetContentClient()->browser()->GetMediaObserver();
+  // Check if the embedder isn't interested in the notification.
+  if (media_observer == NULL)
+    return;
   content::MediaStreamDevices closed_devices;
   DevicesFromRequest(request, &closed_devices);
   if (closed_devices.empty())