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

content/browser/renderer_host/media/media_stream_manager.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/media/media_stream_manager.h"
 
 #include <list>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
@@ skipping 672 matching lines @@
   DeviceRequests::iterator it = requests_.find(label);
   if (it != requests_.end()) {
     DCHECK_EQ(it->second.type, DeviceRequest::GENERATE_STREAM);
     it->second.requester->StreamGenerationFailed(label);
     requests_.erase(it);
     return;
   }
 }
 
 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();
 }
 
 void MediaStreamManager::WillDestroyCurrentMessageLoop() {
   DCHECK_EQ(MessageLoop::current(), io_loop_);
   DCHECK(requests_.empty());
   if (device_thread_.get()) {
     StopMonitoring();
 
     video_capture_manager_->Unregister();
     audio_input_device_manager_->Unregister();
     device_thread_.reset();
   }
 
   audio_input_device_manager_ = NULL;
   video_capture_manager_ = NULL;
   io_loop_ = NULL;
   device_settings_.reset();
 }
 
 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());
   media_observer->OnCaptureDevicesOpened(request->render_process_id,
                                          request->render_view_id,
                                          opened_devices);
 }
 
 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())
     return;
   media_observer->OnCaptureDevicesClosed(request->render_process_id,
                                          request->render_view_id,
                                          closed_devices);
 }
 
 void MediaStreamManager::DevicesFromRequest(
@@ skipping 113 matching lines @@
        it != requests_.end(); ++it) {
     if (it->second.type == DeviceRequest::ENUMERATE_DEVICES &&
         Requested(it->second.options, stream_type)) {
       return true;
     }
   }
   return false;
 }
 
 }  // namespace media_stream