Decouple capture timestamp and reference time

content/browser/renderer_host/media/video_capture_controller.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_controller.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <map>
@@ skipping 339 matching lines @@
 }
 
 VideoCaptureController::~VideoCaptureController() {
   STLDeleteContainerPointers(controller_clients_.begin(),
                              controller_clients_.end());
 }
 
 void VideoCaptureController::DoIncomingCapturedVideoFrameOnIOThread(
     std::unique_ptr<media::VideoCaptureDevice::Client::Buffer> buffer,
     const scoped_refptr<VideoFrame>& frame,
-    const base::TimeTicks& timestamp) {
+    base::TimeTicks reference_time) {

[miu, 2016/06/07 20:03:47]

(See comment for video_capture_host.cc.) You could have the caller of this
method (or some caller further upstream) set the REFERENCE_TIME field in
|frame|'s metadata. Then, you don't need the 3rd argument to this method.

[qiangchen, 2016/06/08 18:04:30]

Done.

   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   const int buffer_id = buffer->id();
   DCHECK_NE(buffer_id, VideoCaptureBufferPool::kInvalidId);
 
   int count = 0;
   if (state_ == VIDEO_CAPTURE_STATE_STARTED) {
     if (!frame->metadata()->HasKey(VideoFrameMetadata::FRAME_RATE)) {
       frame->metadata()->SetDouble(VideoFrameMetadata::FRAME_RATE,
                                    video_capture_format_.frame_rate);
     }
@@ skipping 18 matching lines @@
 
     for (const auto& client : controller_clients_) {
       if (client->session_closed || client->paused)
         continue;
 
       // On the first use of a buffer on a client, share the memory handles.
       const bool is_new_buffer = client->known_buffers.insert(buffer_id).second;
       if (is_new_buffer)
         DoNewBufferOnIOThread(client, buffer.get(), frame);
 
-      client->event_handler->OnBufferReady(client->controller_id,
-                                           buffer_id,
-                                           frame,
-                                           timestamp);
+      client->event_handler->OnBufferReady(client->controller_id, buffer_id,
+                                           frame, reference_time);
       const bool inserted =
           client->active_buffers.insert(std::make_pair(buffer_id, frame))
               .second;
       DCHECK(inserted) << "Unexpected duplicate buffer: " << buffer_id;
       count++;
     }
   }
 
   if (!has_received_frames_) {
     UMA_HISTOGRAM_COUNTS("Media.VideoCapture.Width",
@@ skipping 97 matching lines @@
     int session_id,
     const ControllerClients& clients) {
   for (auto client : clients) {
     if (client->session_id == session_id)
       return client;
   }
   return NULL;
 }
 
 }  // namespace content