Remove MediaStreamDeviceThread in favor of audio worker TaskRunner.

content/browser/renderer_host/media/media_stream_manager.h

 // 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.
 
 // MediaStreamManager is used to open/enumerate media capture devices (video
 // supported now). Call flow:
 // 1. GenerateStream is called when a render process wants to use a capture
 //    device.
 // 2. MediaStreamManager will ask MediaStreamUIController for permission to
 //    use devices and for which device to use.
@@ skipping 19 matching lines @@
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/system_monitor/system_monitor.h"
 #include "content/browser/renderer_host/media/media_stream_provider.h"
 #include "content/common/content_export.h"
 #include "content/common/media/media_stream_options.h"
 #include "content/public/browser/media_request_state.h"
 
-namespace base {
-class Thread;
-}
-
 namespace media {
 class AudioManager;
 }
 
 namespace content {
 
 class AudioInputDeviceManager;
 class FakeMediaStreamUIProxy;
 class MediaStreamDeviceSettings;
 class MediaStreamRequester;
@@ skipping 275 matching lines @@
   // Finds and returns the device id corresponding to the given
   // |source_id|. Returns true if there was a raw device id that matched the
   // given |source_id|, false if nothing matched it.
   bool TranslateSourceIdToDeviceId(
       MediaStreamType stream_type,
       ResourceContext* rc,
       const GURL& security_origin,
       const std::string& source_id,
       std::string* device_id) const;
 
-  // Device thread shared by VideoCaptureManager and AudioInputDeviceManager.
-  scoped_ptr<base::Thread> device_thread_;
+  // Task runner shared by VideoCaptureManager and AudioInputDeviceManager.
+  // Note: Enumeration tasks may take seconds to complete so must never be run
+  // on any of the BrowserThreads (UI, IO, etc).  See http://crbug.com/256945.
+  scoped_refptr<base::SingleThreadTaskRunner> device_task_runner_;
 
   media::AudioManager* const audio_manager_;  // not owned
   scoped_refptr<AudioInputDeviceManager> audio_input_device_manager_;
   scoped_refptr<VideoCaptureManager> video_capture_manager_;
 
   // Indicator of device monitoring state.
   bool monitoring_started_;
 
   // Stores most recently enumerated device lists. The cache is cleared when
   // monitoring is stopped or there is no request for that type of device.
@@ skipping 13 matching lines @@
 
   bool use_fake_ui_;
   scoped_ptr<FakeMediaStreamUIProxy> fake_ui_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaStreamManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_MEDIA_STREAM_MANAGER_H_