Decouple capture timestamp and reference time

media/capture/video/linux/v4l2_capture_delegate.cc

Index: media/capture/video/linux/v4l2_capture_delegate.cc
diff --git a/media/capture/video/linux/v4l2_capture_delegate.cc b/media/capture/video/linux/v4l2_capture_delegate.cc
index bc0ef75917d55b539f831edd49294446ac5bc893..6e222efccc335fc96f5d75c1c7ba5ab72cffbe2b 100644
--- a/media/capture/video/linux/v4l2_capture_delegate.cc
+++ b/media/capture/video/linux/v4l2_capture_delegate.cc
@@ -390,9 +390,12 @@ void V4L2CaptureDelegate::DoCapture() {
     buffer_tracker_pool_[buffer.index]->set_payload_size(buffer.bytesused);
     const scoped_refptr<BufferTracker>& buffer_tracker =
         buffer_tracker_pool_[buffer.index];
+    base::TimeTicks now = base::TimeTicks::Now();
+    if (first_ref_time_.is_null())
+      first_ref_time_ = now;

[miu, 2016/05/18 22:35:40]

The |buffer| has a |timestamp| field you can translate:

  base::TimeDelta timestamp =
      base::TimeDelta::FromSeconds(buffer.timestamp.tv_sec) +
      base::TimeDelta::FromMicroseconds(buffer.timestamp.tv_usec);

...so you don't need the |first_ref_time_| mechanism here. :)

[qiangchen, 2016/05/20 17:55:14]

Done.

     client_->OnIncomingCapturedData(
         buffer_tracker->start(), buffer_tracker->payload_size(),
-        capture_format_, rotation_, base::TimeTicks::Now());
+        capture_format_, rotation_, now, now - first_ref_time_);
 
     if (HANDLE_EINTR(ioctl(device_fd_.get(), VIDIOC_QBUF, &buffer)) < 0) {
       SetErrorState(FROM_HERE, "Failed to enqueue capture buffer");