Enable H.264 video WebRTC behind run-time flag and add WebRtcBrowserTest for H.264

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 a2e3f181293aa9ab8882e332226225069aee0776..472249e64b89ccbf4d04ff1d2cfb50d84ba882f8 100644
--- a/content/renderer/media/webrtc/peer_connection_dependency_factory.cc
+++ b/content/renderer/media/webrtc/peer_connection_dependency_factory.cc
@@ -263,19 +263,10 @@ void PeerConnectionDependencyFactory::CreatePeerConnectionFactory() {
   DVLOG(1) << "PeerConnectionDependencyFactory::CreatePeerConnectionFactory()";
 
 #if BUILDFLAG(RTC_USE_H264)
-  // TODO(hbos): This is temporary. Disable the runtime effects of building with
-  // |rtc_use_h264|. We are planning to default the |rtc_use_h264| flag to
-  // |proprietary_codecs| so that it will be used by Chromium trybots. This
-  // would also make it used by Chrome, but this feature is not ready to be
-  // launched yet. An upcoming CL will add browser tests for H264. That CL will
-  // remove this line. It should remain disabled until tested.
-  webrtc::DisableRtcUseH264();
   // When building with |rtc_use_h264|, |H264DecoderImpl| may be used which
   // depends on FFmpeg, therefore we need to initialize FFmpeg before going
   // further.
-  // TODO(hbos): Temporarily commented out due to webrtc::DisableRtcUseH264(),
-  // no need to initialize FFmpeg when |H264DecoderImpl| is disabled.
-  // media::FFmpegGlue::InitializeFFmpeg();
+  media::FFmpegGlue::InitializeFFmpeg();
 #endif
 
   base::MessageLoop::current()->AddDestructionObserver(this);