Ability to disable the effects of |rtc_use_h264| with DisableRtcUseH264.

webrtc/modules/video_coding/codecs/h264/include/h264.h

Index: webrtc/modules/video_coding/codecs/h264/include/h264.h
diff --git a/webrtc/modules/video_coding/codecs/h264/include/h264.h b/webrtc/modules/video_coding/codecs/h264/include/h264.h
index 7f0bbf042beddc0f091fa2779e7789a732dccead..2c404b2cef6878b12a6c54a7d27cba27c05026d7 100644
--- a/webrtc/modules/video_coding/codecs/h264/include/h264.h
+++ b/webrtc/modules/video_coding/codecs/h264/include/h264.h
@@ -27,6 +27,12 @@
 
 namespace webrtc {
 
+// Set to disable the H.264 encoder/decoder implementations that are provided if
+// |rtc_use_h264| build flag is true (if false, this function does nothing).
+// This function should only be called before or during WebRTC initialization
+// and is not thread-safe.
+void DisableRtcUseH264();
+
 class H264Encoder : public VideoEncoder {
  public:
   static H264Encoder* Create();