Refactor how the DeviceMonitor is started.

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 <vector>
 
 #include "base/bind.h"
@@ skipping 395 matching lines @@
 
 std::string MediaStreamManager::EnumerateDevices(
     MediaStreamRequester* requester,
     int render_process_id,
     int render_view_id,
     ResourceContext* rc,
     int page_request_id,
     MediaStreamType type,
     const GURL& security_origin) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  DCHECK(requester);
   DCHECK(type == MEDIA_DEVICE_AUDIO_CAPTURE ||
          type == MEDIA_DEVICE_VIDEO_CAPTURE);
 
-  // When the requester is NULL, the request is made by the UI to ensure MSM
-  // starts monitoring devices.
-  if (!requester) {
-    if (!monitoring_started_)
-      StartMonitoring();
-
-    return std::string();
-  }
-
   // Create a new request.
   StreamOptions options;
   if (type == MEDIA_DEVICE_AUDIO_CAPTURE) {
     options.audio_type = type;
   } else if (type == MEDIA_DEVICE_VIDEO_CAPTURE) {
     options.video_type = type;
   } else {
     NOTREACHED();
     return std::string();
   }
@@ skipping 89 matching lines @@
   // been stopped.
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE,
       base::Bind(&MediaStreamManager::SetupRequest,
                  base::Unretained(this), label));
 
   DVLOG(1) << "OpenDevice ({label = " << label <<  "})";
   return label;
 }
 
+void MediaStreamManager::EnsureDeviceMonitorStarted() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  if (!monitoring_started_)
+    StartMonitoring();
+}
+
 void MediaStreamManager::StopRemovedDevices(
     const StreamDeviceInfoArray& old_devices,
     const StreamDeviceInfoArray& new_devices) {
   DVLOG(1) << "StopRemovedDevices("
            << "{#old_devices = " << old_devices.size() <<  "} "
            << "{#new_devices = " << new_devices.size() << "})";
   for (StreamDeviceInfoArray::const_iterator old_dev_it = old_devices.begin();
        old_dev_it != old_devices.end(); ++old_dev_it) {
     bool device_found = false;
     for (StreamDeviceInfoArray::const_iterator new_dev_it = new_devices.begin();
@@ skipping 871 matching lines @@
   }
 
   // Always do enumeration even though some enumeration is in progress,
   // because those enumeration commands could be sent before these devices
   // change.
   ++active_enumeration_ref_count_[stream_type];
   GetDeviceManager(stream_type)->EnumerateDevices(stream_type);
 }
 
 }  // namespace content