RESOURCE_UTILIZATION in VideoFrameMetadata, a consumer feedback signal.

content/browser/renderer_host/media/video_capture_host.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.
 //
 // VideoCaptureHost serves video capture related messages from
 // VideoCaptureMessageFilter which lives inside the render process.
 //
 // This class is owned by RenderProcessHostImpl, and instantiated on UI
 // thread, but all other operations and method calls happen on IO thread.
 //
@@ skipping 113 matching lines @@
   // IPC message: Stop capture on device referenced by |device_id|.
   void OnStopCapture(int device_id);
 
   // IPC message: Pause capture on device referenced by |device_id|.
   void OnPauseCapture(int device_id);
 
   void OnResumeCapture(int device_id,
                        media::VideoCaptureSessionId session_id,
                        const media::VideoCaptureParams& params);
 
-  // IPC message: Receive an empty buffer from renderer. Send it to device
-  // referenced by |device_id|.
-  void OnReceiveEmptyBuffer(int device_id, int buffer_id, uint32 sync_point);
+  // IPC message: Called when a renderer is finished using a buffer. Notifies
+  // the controller.
+  void OnRendererFinishedWithBuffer(int device_id,
+                                    int buffer_id,
+                                    uint32 sync_point,
+                                    double consumer_resource_utilization);
 
   // IPC message: Get supported formats referenced by |capture_session_id|.
   // |device_id| is needed for message back-routing purposes.
   void OnGetDeviceSupportedFormats(
       int device_id,
       media::VideoCaptureSessionId capture_session_id);
 
   // IPC message: Get a device's currently in use format(s), referenced by
   // |capture_session_id|. |device_id| is needed for message back-routing
   // purposes.
@@ skipping 14 matching lines @@
   // is connected. An entry in this map holds a null controller while it is in
   // the process of starting.
   EntryMap entries_;
 
   DISALLOW_COPY_AND_ASSIGN(VideoCaptureHost);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_HOST_H_