Preparation CL for H264 support in WebRTC.

content/renderer/media/webrtc/peer_connection_dependency_factory.cc

Index: content/renderer/media/webrtc/peer_connection_dependency_factory.cc
diff --git a/content/renderer/media/webrtc/peer_connection_dependency_factory.cc b/content/renderer/media/webrtc/peer_connection_dependency_factory.cc
index 270cf169851d51f21a8a5377d7bacf87f2b222e7..0784a11756cd1bb37ea8ea77aeb1287fce7f2acd 100644
--- a/content/renderer/media/webrtc/peer_connection_dependency_factory.cc
+++ b/content/renderer/media/webrtc/peer_connection_dependency_factory.cc
@@ -55,6 +55,7 @@
 #include "crypto/openssl_util.h"
 #include "jingle/glue/thread_wrapper.h"
 #include "media/base/media_permission.h"
+#include "media/filters/ffmpeg_glue.h"
 #include "media/renderers/gpu_video_accelerator_factories.h"
 #include "third_party/WebKit/public/platform/WebMediaConstraints.h"
 #include "third_party/WebKit/public/platform/WebMediaStream.h"
@@ -259,6 +260,14 @@ void PeerConnectionDependencyFactory::CreatePeerConnectionFactory() {
 
   DVLOG(1) << "PeerConnectionDependencyFactory::CreatePeerConnectionFactory()";
 
+#if defined(WEBRTC_USE_H264)
+  // When building with |rtc_use_h264|, FFmpeg must be initialized externally
+  // from WebRTC before any |H264DecoderImpl| is initialized. By initializing
+  // here we guarantee that FFmpeg has been initialized before any decoders are
+  // used.

[tommi (sloooow) - chröme, 2016/02/01 17:51:20]

"must be initialized externally from WebRTC" is a bit confusing.

Can we say that H264DecoderImpl depends on ffmpeg for h264 decoding and
therefore we need to initialize ffmpeg before going further?

[hbos_chromium, 2016/02/02 14:20:12]

Done.

+  media::FFmpegGlue::InitializeFFmpeg();
+#endif
+
   base::MessageLoop::current()->AddDestructionObserver(this);
   // To allow sending to the signaling/worker threads.
   jingle_glue::JingleThreadWrapper::EnsureForCurrentMessageLoop();