Add TestBrowserThreadBundle into RenderViewHostTestHarness. Kill some unnecessary real threads.

chrome/browser/media/media_capture_devices_dispatcher.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.
 
 #ifndef CHROME_BROWSER_MEDIA_MEDIA_CAPTURE_DEVICES_DISPATCHER_H_
 #define CHROME_BROWSER_MEDIA_MEDIA_CAPTURE_DEVICES_DISPATCHER_H_
 
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/singleton.h"
@@ skipping 73 matching lines @@
 
   // Helper for picking the device that was requested for an OpenDevice request.
   // If the device requested is not available it will revert to using the first
   // available one instead or will return an empty list if no devices of the
   // requested kind are present.
   void GetRequestedDevice(const std::string& requested_device_id,
                           bool audio,
                           bool video,
                           content::MediaStreamDevices* devices);
 
+  // Unittests that do not require actual device enumeration should call this
+  // API on the singleton. It is safe to call this multiple times on the
+  // signleton.
+  void DisableDeviceEnumerationForTesting();
+
   // Overridden from content::MediaObserver:
   virtual void OnAudioCaptureDevicesChanged(
       const content::MediaStreamDevices& devices) OVERRIDE;
   virtual void OnVideoCaptureDevicesChanged(
       const content::MediaStreamDevices& devices) OVERRIDE;
   virtual void OnMediaRequestStateChanged(
       int render_process_id,
       int render_view_id,
       const content::MediaStreamDevice& device,
       content::MediaRequestState state) OVERRIDE;
@@ skipping 39 matching lines @@
   // A list of cached video capture devices.
   content::MediaStreamDevices video_devices_;
 
   // A list of observers for the device update notifications.
   ObserverList<Observer> observers_;
 
   // Flag to indicate if device enumeration has been done/doing.
   // Only accessed on UI thread.
   bool devices_enumerated_;
 
+  // Flag used by unittests to disable device enumeration.
+  bool is_device_enumeration_disabled_;
+
   scoped_refptr<MediaStreamCaptureIndicator> media_stream_capture_indicator_;
 
   scoped_refptr<AudioStreamIndicator> audio_stream_indicator_;
 };
 
 #endif  // CHROME_BROWSER_MEDIA_MEDIA_CAPTURE_DEVICES_DISPATCHER_H_