Use NTP time for video frame timestamp.

Add tracing for capture timestamps.

BUG=225209


Review URL: https://chromiumcodereview.appspot.com/13554003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@192670 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/renderer_host/media/web_contents_video_capture_device.cc

@@ -517,8 +517,9 @@ void CaptureOracle::DidCaptureFrame(
     bool success) {
   base::AutoLock guard(lock_);
 
-  TRACE_EVENT_ASYNC_END1("mirroring", "Capture", frame.get(),
-                         "success", success);
+  TRACE_EVENT_ASYNC_END2("mirroring", "Capture", frame.get(),
+                         "success", success,
+                         "timestamp", timestamp.ToInternalValue());
 
   if (!consumer_ || !is_started_)
     return;  // Capture is stopped.

content/renderer/media/rtc_video_capturer.cc

@@ -5,6 +5,7 @@
 #include "content/renderer/media/rtc_video_capturer.h"
 
 #include "base/bind.h"
+#include "base/debug/trace_event.h"
 
 namespace content {
 
@@ -15,6 +16,17 @@ RtcVideoCapturer::RtcVideoCapturer(
     : is_screencast_(is_screencast),
       delegate_(new RtcVideoCaptureDelegate(id, vc_manager)),
       state_(VIDEO_CAPTURE_STATE_STOPPED) {
+  base::Time::Exploded exploded = {};
+  exploded.year = 1900;
+  exploded.month = 1;
+  exploded.day_of_week = 0;
+  exploded.day_of_month = 1;
+  exploded.hour = 0;
+  exploded.minute = 0;
+  exploded.second = 0;
+  exploded.millisecond = 0;
+  DCHECK(exploded.HasValidValues());
+  ntp_epoch_ = base::Time::FromUTCExploded(exploded);
 }
 
 RtcVideoCapturer::~RtcVideoCapturer() {
@@ -100,11 +112,20 @@ void RtcVideoCapturer::OnFrameCaptured(
   // cricket::CapturedFrame time is in nanoseconds.
   frame.elapsed_time = (buf.timestamp - start_time_).InMicroseconds() *
       base::Time::kNanosecondsPerMicrosecond;
-  frame.time_stamp = frame.elapsed_time;
+  // Timestamp in NTP time (seconds since 0:00 UTC 1 January 1900) in ms.
+  frame.time_stamp = (buf.timestamp - ntp_epoch_).InMilliseconds();
   frame.data = buf.memory_pointer;
   frame.pixel_height = 1;
   frame.pixel_width = 1;
 
+  TRACE_EVENT_INSTANT2("rtc_video_capturer",
+                       "OnFrameCaptured",
+                       TRACE_EVENT_SCOPE_THREAD,
+                       "elapsed time",
+                       frame.elapsed_time,
+                       "timestamp",
+                       frame.time_stamp);
+
   // This signals to libJingle that a new VideoFrame is available.
   // libJingle have no assumptions on what thread this signal come from.
   SignalFrameCaptured(this, &frame);

content/renderer/media/rtc_video_capturer.h

@@ -51,6 +51,7 @@ class RtcVideoCapturer
   scoped_refptr<RtcVideoCaptureDelegate> delegate_;
   VideoCaptureState state_;
   base::Time start_time_;
+  base::Time ntp_epoch_;
 
   DISALLOW_COPY_AND_ASSIGN(RtcVideoCapturer);
 };