Fix timestamp issue in RTCVideoEncoder for native frames

Speculative fix for WebRTC test failures. See issue for more information.

BUG=732345
TBR=emircan

Review-Url: https://codereview.chromium.org/2934793002
Cr-Commit-Position: refs/heads/master@{#478627}

content/renderer/media/gpu/rtc_video_encoder.cc

@@ -618,8 +618,15 @@ void RTCVideoEncoder::Impl::EncodeOneFrame() {
   }
 
   if (requires_copy) {
+    // TODO(magjed/emircan): This check is needed in order for the
+    // |pending_timestamps_| DHCECK below to not fail. It shouldn't be
+    // necessary.
+    const bool use_media_timestamp =
+        frame && (frame->HasTextures() ||
+                  frame->storage_type() == media::VideoFrame::STORAGE_SHMEM);
     const base::TimeDelta timestamp =
-        frame ? frame->timestamp()
+        use_media_timestamp
+            ? frame->timestamp()
             : base::TimeDelta::FromMilliseconds(next_frame->ntp_time_ms());
     base::SharedMemory* input_buffer = input_buffers_[index].get();
     frame = media::VideoFrame::WrapExternalSharedMemory(