[RTCInsertableStreams] Always sync JS ArrayBuffer with internal buffer.

It is possible to modify the data field without replacing it, so syncing
always where both a delegate frame and JS buffer exist.
Drive-by: handle cases with no delegate in other methods.

Bug: 1052765
Change-Id: I4cc1383b584d9d9f4334e0da1b6d7c092f94821d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2084855Reviewed-by: Harald Alvestrand <hta@chromium.org>
Commit-Queue: Guido Urdaneta <guidou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#746494}

third_party/blink/renderer/modules/peerconnection/rtc_encoded_video_frame.cc

@@ -25,7 +25,7 @@ String RTCEncodedVideoFrame::type() const {
 }
 
 uint64_t RTCEncodedVideoFrame::timestamp() const {
-  return delegate_->ReceivedTime();
+  return delegate_ ? delegate_->ReceivedTime() : 0;
 }
 
 DOMArrayBuffer* RTCEncodedVideoFrame::data() const {
@@ -46,7 +46,6 @@ DOMArrayBuffer* RTCEncodedVideoFrame::additionalData() const {
 
 void RTCEncodedVideoFrame::setData(DOMArrayBuffer* data) {
   frame_data_ = data;
-  replaced_frame_data_ = true;
 }
 
 String RTCEncodedVideoFrame::toString() const {
@@ -67,7 +66,7 @@ String RTCEncodedVideoFrame::toString() const {
 std::unique_ptr<webrtc::video_coding::EncodedFrame>
 RTCEncodedVideoFrame::PassDelegate() {
   // Sync the delegate data with |frame_data_| if necessary.
-  if (replaced_frame_data_) {
+  if (delegate_ && frame_data_) {
     rtc::scoped_refptr<webrtc::EncodedImageBuffer> webrtc_image =
         webrtc::EncodedImageBuffer::Create(
             static_cast<const uint8_t*>(frame_data_->Data()),

third_party/blink/renderer/modules/peerconnection/rtc_encoded_video_frame.h

@@ -52,7 +52,6 @@ class MODULES_EXPORT RTCEncodedVideoFrame final : public ScriptWrappable {
  private:
   std::unique_ptr<webrtc::video_coding::EncodedFrame> delegate_;
   std::vector<uint8_t> additional_data_vector_;
-  bool replaced_frame_data_ = false;
   // Exposes encoded frame data from |delegate_|.
   mutable Member<DOMArrayBuffer> frame_data_;
   // Exposes data from |additional_data_vector_|.