Refactor how the DeviceMonitor is started.

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 7451d1adbf8998ca15c59a3c8ab1ca2e1bd8c009..0c30e280d5462b9554412adfab26234b3f4bec5d 100644
--- a/content/browser/renderer_host/media/media_stream_manager.cc
+++ b/content/browser/renderer_host/media/media_stream_manager.cc
@@ -150,6 +150,7 @@ class MediaStreamManager::DeviceRequest {
   std::vector<MediaRequestState> state_;
 };
 
+
 MediaStreamManager::EnumerationCache::EnumerationCache()
     : valid(false) {
 }
@@ -414,15 +415,7 @@ std::string MediaStreamManager::EnumerateDevices(
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   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();
-  }
+  DCHECK(requester);
 
   // Create a new request.
   StreamOptions options;