Decouple capture timestamp and reference time

media/capture/video/linux/v4l2_capture_delegate.h

 // Copyright 2015 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.
 
 #ifndef MEDIA_VIDEO_CAPTURE_LINUX_V4L2_VIDEO_CAPTURE_DELEGATE_H_
 #define MEDIA_VIDEO_CAPTURE_LINUX_V4L2_VIDEO_CAPTURE_DELEGATE_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 72 matching lines @@
   // Vector of BufferTracker to keep track of mmap()ed pointers and their use.
   class BufferTracker;
   std::vector<scoped_refptr<BufferTracker>> buffer_tracker_pool_;
 
   bool is_capturing_;
   int timeout_count_;
 
   // Clockwise rotation in degrees. This value should be 0, 90, 180, or 270.
   int rotation_;
 
+  // The system time when we receive the first frame.
+  base::TimeTicks first_ref_time_;
+
   DISALLOW_COPY_AND_ASSIGN(V4L2CaptureDelegate);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_VIDEO_CAPTURE_LINUX_V4L2_VIDEO_CAPTURE_DELEGATE_H_