Enable RTCVideoDecoder SW H264 fallback only when it is available

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 544b25e2c35445d10f8f980337071e3f570ce64a..c995d5009027f0a2726c2e14d798266e9f94332f 100644
--- a/content/renderer/media/webrtc/peer_connection_dependency_factory.cc
+++ b/content/renderer/media/webrtc/peer_connection_dependency_factory.cc
@@ -164,7 +164,9 @@ void PeerConnectionDependencyFactory::CreatePeerConnectionFactory() {
 
 #if BUILDFLAG(RTC_USE_H264)
   // Building /w |rtc_use_h264|, is the corresponding run-time feature enabled?
-  if (base::FeatureList::IsEnabled(kWebRtcH264WithOpenH264FFmpeg)) {
+  if (base::FeatureList::IsEnabled(kWebRtcH264WithOpenH264FFmpeg) ||
+      base::CommandLine::ForCurrentProcess()->HasSwitch(
+          kEnableWebRtcHWH264Encoding)) {

[hbos_chromium, 2016/06/02 08:45:37]

I don't think this is the right approach. If we're building with SW H264, one
feature unexpectedly enables another feature (that might be set to disabled
which is strange). If we're not building with SW H264 (such as chromium build
instead of a chrome official) this does not fix anything, we still have the
problem of trying to do SW fallback when SW is not available.

I'll continue the discussion at
https://bugs.chromium.org/p/chromium/issues/detail?id=615513

[emircan, 2016/06/02 20:54:32]

Done.

     // |H264DecoderImpl| may be used which depends on FFmpeg, therefore we need
     // to initialize FFmpeg before going further.
     media::FFmpegGlue::InitializeFFmpeg();