Use webrtc::VideoFrame timestamp in RTCVideoEncoder

content/renderer/media/gpu/rtc_video_encoder.cc

Index: content/renderer/media/gpu/rtc_video_encoder.cc
diff --git a/content/renderer/media/gpu/rtc_video_encoder.cc b/content/renderer/media/gpu/rtc_video_encoder.cc
index 7ec22b2f3d0a9996ed3ea0f422d9432e8c303567..7a9514e7f5cec07a8b0c76f65b48b8002c8999b0 100644
--- a/content/renderer/media/gpu/rtc_video_encoder.cc
+++ b/content/renderer/media/gpu/rtc_video_encoder.cc
@@ -32,6 +32,9 @@ namespace content {
 
 namespace {
 
+// Used for timestamp conversions.
+static const int kMsToRtpTimestamp = 90;
+
 // Translate from webrtc::VideoCodecType and webrtc::VideoCodec to
 // media::VideoCodecProfile.
 media::VideoCodecProfile WebRTCVideoCodecToVideoCodecProfile(
@@ -486,8 +489,9 @@ void RTCVideoEncoder::Impl::BitstreamBufferReady(int32_t bitstream_buffer_id,
     capture_time_ms = capture_time_us / base::Time::kMicrosecondsPerMillisecond;
   }
   // RTP timestamp can wrap around. Get the lower 32 bits.
-  rtp_timestamp = static_cast<uint32_t>(
-      capture_time_us * 90 / base::Time::kMicrosecondsPerMillisecond);
+  rtp_timestamp =
+      static_cast<uint32_t>(capture_time_us * kMsToRtpTimestamp /
+                            base::Time::kMicrosecondsPerMillisecond);
 
   webrtc::EncodedImage image(
       reinterpret_cast<uint8_t*>(output_buffer->memory()), payload_size,
@@ -571,15 +575,13 @@ void RTCVideoEncoder::Impl::EncodeOneFrame() {
   }
 
   if (requires_copy) {
-    const base::TimeDelta timestamp =
-        frame ? frame->timestamp()
-              : base::TimeDelta::FromMilliseconds(next_frame->ntp_time_ms());
     base::SharedMemory* input_buffer = input_buffers_[index];
     frame = media::VideoFrame::WrapExternalSharedMemory(
         media::PIXEL_FORMAT_I420, input_frame_coded_size_,
         gfx::Rect(input_visible_size_), input_visible_size_,
         reinterpret_cast<uint8_t*>(input_buffer->memory()),
-        input_buffer->mapped_size(), input_buffer->handle(), 0, timestamp);
+        input_buffer->mapped_size(), input_buffer->handle(), 0,
+        base::TimeDelta());
     if (!frame.get()) {
       LogAndNotifyError(FROM_HERE, "failed to create frame",
                         media::VideoEncodeAccelerator::kPlatformFailureError);
@@ -606,6 +608,11 @@ void RTCVideoEncoder::Impl::EncodeOneFrame() {
       return;
     }
   }
+  // Use the timestamp set from WebRTC and convert it from 90 kHz.
+  frame->set_timestamp(
+      base::TimeDelta::FromMicroseconds(
+          next_frame->timestamp() * base::Time::kMicrosecondsPerMillisecond /
+          kMsToRtpTimestamp));
   frame->AddDestructionObserver(media::BindToCurrentLoop(
       base::Bind(&RTCVideoEncoder::Impl::EncodeFrameFinished, this, index)));
   video_encoder_->Encode(frame, next_frame_keyframe);