Pass a TimeTicks along video capture pipeline to represent capture time

content/common/media/video_capture.h

 // Copyright (c) 2011 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.
 //
 // This file contains commonly used definitions of video capture.
 
 #ifndef CONTENT_COMMON_MEDIA_VIDEO_CAPTURE_H_
 #define CONTENT_COMMON_MEDIA_VIDEO_CAPTURE_H_
 
 #include "base/time/time.h"
@@ skipping 14 matching lines @@
   VIDEO_CAPTURE_STATE_STOPPED,
   VIDEO_CAPTURE_STATE_ERROR,
   VIDEO_CAPTURE_STATE_ENDED,
   VIDEO_CAPTURE_STATE_LAST = VIDEO_CAPTURE_STATE_ENDED
 };
 
 typedef base::Callback<void(VideoCaptureState)>
     VideoCaptureStateUpdateCB;
 typedef base::Callback<void(const media::VideoCaptureFormats&)>
     VideoCaptureDeviceFormatsCB;
+

[Alpha Left Google, 2014/05/31 00:34:50]

I have moved the definition of this callback to media_stream_video_sink.h to
avoid duplicated definition.

+// This callback is used to deliver video frames.
+// |video_frame| - An object of a video frame.
+// |format| - Format and additional information such as frame rate.

[Ami GONE FROM CHROMIUM, 2014/05/19 19:01:46]

neither of these 2 lines are adding value.

[Alpha Left Google, 2014/05/31 00:34:50]

Done.

+// |start_ticks| - An optional field to provide additional timing
+// information for the beginning of this stream of video frames.

[Ami GONE FROM CHROMIUM, 2014/05/19 19:01:46]

These 2 lines would be clearer as:
The time at the start of this stream, if available.

+// This field usually means the local time when the first video frame of
+// this stream is generated. It is possible for this value to be null if

[Ami GONE FROM CHROMIUM, 2014/05/19 19:01:46]

s/stream is/stream was/

[Alpha Left Google, 2014/05/31 00:34:50]

Done.

+// this timing information cannot be determined. There is no gurantee that

[Ami GONE FROM CHROMIUM, 2014/05/19 19:01:46]

typo: gurantee

[Alpha Left Google, 2014/05/31 00:34:50]

Done.

+// this value is accurate. For example video frames from a remote source
+// can only provide this timing information as an estimation.

[Ami GONE FROM CHROMIUM, 2014/05/19 19:01:46]

estimation -> estimate

[Alpha Left Google, 2014/05/31 00:34:50]

Done.

+// This field is used for synchronization with other audio or video streams.
+// |video_frame->timestamp() + start_ticks| will give an estimation in local

[Ami GONE FROM CHROMIUM, 2014/05/19 19:01:46]

estimation -> estimate

[Alpha Left Google, 2014/05/31 00:34:50]

Done.

+// time when the frame is generated.

[Ami GONE FROM CHROMIUM, 2014/05/19 19:01:46]

s/is/was/

 typedef base::Callback<
-  void(const scoped_refptr<media::VideoFrame>&,
-       const media::VideoCaptureFormat&)>
+  void(const scoped_refptr<media::VideoFrame>& video_frame,
+       const media::VideoCaptureFormat& format,
+       const base::TimeTicks& start_ticks)>
     VideoCaptureDeliverFrameCB;
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_MEDIA_VIDEO_CAPTURE_H_