RTC Video Encoder: implement timestamp fallback

content/renderer/media/rtc_video_encoder.cc

Index: content/renderer/media/rtc_video_encoder.cc
diff --git a/content/renderer/media/rtc_video_encoder.cc b/content/renderer/media/rtc_video_encoder.cc
index 4ce16d53834017eb35d2ea0a9922398047144ef6..df1a458dda1e904390783b23786dd0734f9fe8e7 100644
--- a/content/renderer/media/rtc_video_encoder.cc
+++ b/content/renderer/media/rtc_video_encoder.cc
@@ -473,19 +473,24 @@ void RTCVideoEncoder::Impl::BitstreamBufferReady(int32_t bitstream_buffer_id,
   }
   output_buffers_free_count_--;
 
-  // Derive the capture time (in ms) and RTP timestamp (in 90KHz ticks).
-  // This is based on how input timestamps are calculated in
-  // webrtc/video/video_capture_input.cc.
-  const uint32_t rtp_timestamp =
-      static_cast<uint32_t>(timestamp.InMilliseconds()) * 90;
+  uint32_t capture_time_ms = 0;
+  //if (timestamp.is_zero()) {
+    // Some platform does not pass captured timestamp through. Use the current
+    // time instead.
+    capture_time_ms = rtc::TimeMicros() / 1000;
+  //} else {
+  //  capture_time_ms = static_cast<uint32_t>(timestamp.InMilliseconds());
+  //}
 
   webrtc::EncodedImage image(
       reinterpret_cast<uint8_t*>(output_buffer->memory()), payload_size,
       output_buffer->mapped_size());
   image._encodedWidth = input_visible_size_.width();
   image._encodedHeight = input_visible_size_.height();
-  image._timeStamp = rtp_timestamp;
-  image.capture_time_ms_ = timestamp.InMilliseconds();
+  // This is based on how input timestamps are calculated in
+  // webrtc/video/video_capture_input.cc.
+  image._timeStamp = capture_time_ms * 90;
+  image.capture_time_ms_ = capture_time_ms;
   image._frameType =
       (key_frame ? webrtc::kVideoFrameKey : webrtc::kVideoFrameDelta);
   image._completeFrame = true;