Effects Pepper Plugin and MediaStream Glue.

content/renderer/media/video_source_handler.cc

+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/renderer/media/video_source_handler.h"
+
+#include <string>
+
+#include "base/logging.h"
+#include "content/renderer/media/media_stream_dependency_factory.h"
+#include "content/renderer/render_thread_impl.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebMediaStreamRegistry.h"
+
+using cricket::VideoFrame;
+using webrtc::VideoSourceInterface;
+
+namespace content {
+
+PpFrameReader::PpFrameReader() {
+}
+
+PpFrameReader::~PpFrameReader() {
+}
+
+bool PpFrameReader::SetSize(int width, int height, int reserved) {
+  return true;
+}
+
+bool PpFrameReader::RenderFrame(const VideoFrame* frame) {
+  base::AutoLock auto_lock(lock_);
+  // Make a shallow copy of the frame. Both frames will share a single
+  // reference-counted frame buffer.
+  last_frame_.reset(frame->Copy());
+  return true;
+}
+
+bool PpFrameReader::GetFrame(VideoFrame** frame) {
+  base::AutoLock auto_lock(lock_);
+  *frame = last_frame_.release();
+  return true;
+}
+
+VideoSourceHandler::VideoSourceHandler(
+    MediaStreamDependencyFactory* factory,
+    MediaStreamRegistryInterface* registry)

[wjia(left Chromium), 2013/04/30 18:32:11]

How is it guaranteed that we won't have use-after-free case for factory and/or
registry? Would it make sense to use something like weak ptr?

[Ronghua Wu (Left Chromium), 2013/04/30 22:42:17]

The VideoSourceHandler doesn't take the ownership of the factory and registry. I
expect the user of this class will take care of this. 

+    : factory_(factory),
+      registry_(registry) {
+  ASSERT(factory_ != NULL);
+}
+
+bool VideoSourceHandler::Open(const std::string& url,
+                              FrameReaderInterface** frame_reader) {
+  scoped_refptr<webrtc::VideoSourceInterface> source = GetFirstVideoSource(url);
+  if (!source.get()) {
+    return false;
+  }
+  PpFrameReader* new_frame_reader = new PpFrameReader();

[wjia(left Chromium), 2013/04/30 18:32:11]

It seems that PpFrameReader is an internal class to this file since it would be
used as cricket::VideoRenderer and FrameReaderInterface by others. In other
words, PpFrameReader is not visible to other classes.

[Ronghua Wu (Left Chromium), 2013/04/30 22:42:17]

Correct, I left it in the header more for the testing purpose. 

+  source->AddSink(new_frame_reader);
+  *frame_reader = new_frame_reader;
+  return true;
+}
+
+bool VideoSourceHandler::Close(const std::string& url,
+                               FrameReaderInterface* frame_reader) {
+  scoped_refptr<webrtc::VideoSourceInterface> source = GetFirstVideoSource(url);
+  if (!source.get()) {
+    return false;
+  }
+  PpFrameReader* pp_frame_reader = static_cast<PpFrameReader*>(frame_reader);
+  source->RemoveSink(pp_frame_reader);
+  return true;
+}
+
+scoped_refptr<VideoSourceInterface> VideoSourceHandler::GetFirstVideoSource(

[wjia(left Chromium), 2013/04/30 18:32:11]

Is it possible move this function into media_stream_impl.cc? It seems it has
most of the logic similar/same to what media_stream_impl has.

[Ronghua Wu (Left Chromium), 2013/04/30 22:42:17]

I think MediaStreamImpl is suppose be used by WebKit? We don't have access to it
from here. 

So might be easier to keep it here as a local helper function?

+    const std::string& url) {
+  scoped_refptr<webrtc::VideoSourceInterface> source;
+  WebKit::WebMediaStream stream;
+  if (registry_) {
+    stream = registry_->GetMediaStream(url);
+  } else {
+    stream =
+        WebKit::WebMediaStreamRegistry::lookupMediaStreamDescriptor(GURL(url));
+  }
+  if (stream.isNull() || !stream.extraData()) {
+    LOG(ERROR) << "GetFirstVideoSource - invalid url: " << url;
+    return source;
+  }
+
+  // Get the first video track from the stream.
+  MediaStreamExtraData* extra_data =
+      static_cast<MediaStreamExtraData*>(stream.extraData());
+  if (!extra_data) {
+    LOG(ERROR) << "GetFirstVideoSource - MediaStreamExtraData is NULL.";
+    return source;
+  }
+  webrtc::MediaStreamInterface* native_stream = extra_data->stream();
+  if (!native_stream) {
+    LOG(ERROR) << "GetFirstVideoSource - native stream is NULL.";
+    return source;
+  }
+  webrtc::VideoTrackVector native_video_tracks =
+      native_stream->GetVideoTracks();
+  if (native_video_tracks.empty()) {
+    LOG(ERROR) << "GetFirstVideoSource - stream has no video track.";
+    return source;
+  }
+  source = native_video_tracks[0]->GetSource();
+  return source;
+}
+
+}  // namespace content
+