Add video frame refresh to MediaStream and VideoCapture stacks.

content/browser/renderer_host/media/video_capture_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/video_capture_manager.h"
 
 #include <algorithm>
 #include <set>
 #include <utility>
 
@@ skipping 650 matching lines @@
     DVLOG(1) << "Got Null entry while resuming capture";
   }
 
   // Do not resume Content Video Capture devices, e.g. Tab or Screen capture.
   if (entry->stream_type != MEDIA_DEVICE_VIDEO_CAPTURE)
     return;
 
   controller->ResumeClient(client_id, client_handler);
 }
 
+void VideoCaptureManager::RequestRefreshFrameForClient(
+    VideoCaptureController* controller) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  if (DeviceEntry* entry = GetDeviceEntryForController(controller)) {
+    if (media::VideoCaptureDevice* device = entry->video_capture_device()) {
+      device_task_runner_->PostTask(
+          FROM_HERE,
+          base::Bind(&media::VideoCaptureDevice::RequestRefreshFrame,

[xjz, 2016/04/05 00:04:43]

VideoCaptureDevice::RequestRefreshFrame() currently is a virtual function with
default no-op implementation (and no other implementations anywhere else). Are
the changes on it going to be in follow up CLs?

[miu, 2016/04/05 20:25:01]

Yep!  :)  I'll ask you to review that one shortly.

+                     // Unretained is safe to use here because |device| would be
+                     // null if it was scheduled for shutdown and destruction,
+                     // and because this task is guaranteed to run before the
+                     // task that destroys the |device|.
+                     base::Unretained(device)));
+    }
+  }
+}
+
 bool VideoCaptureManager::GetDeviceSupportedFormats(
     media::VideoCaptureSessionId capture_session_id,
     media::VideoCaptureFormats* supported_formats) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DCHECK(supported_formats->empty());
 
   SessionMap::iterator it = sessions_.find(capture_session_id);
   if (it == sessions_.end())
     return false;
   DVLOG(1) << "GetDeviceSupportedFormats for device: " << it->second.name;
@@ skipping 296 matching lines @@
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   BrowserThread::PostTaskAndReply(
       BrowserThread::UI, FROM_HERE,
       base::Bind(&AVFoundationGlue::InitializeAVFoundation),
       base::Bind(&VideoCaptureManager::OnDeviceLayerInitialized, this,
                  and_then));
 }
 #endif
 
 }  // namespace content