Add H.264 HW encoder and decoder support for Android.

- Allow to configure MediaCodec Java wrapper to use VP8
and H.264 codec.
- Save H.264 config frames with SPS and PPS NALUs and append them to every key frame.
- Correctly handle the case when one encoded frame may generate several output NALUs.
- Add code to find H.264 start codes.
- Add a flag (non configurable yet) to use H.264 in AppRTCDemo.
- Improve MediaCodec logging.

R=wzh@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/43379004

Cr-Commit-Position: refs/heads/master@{#8465}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8465 4adac7df-926f-26a2-2b94-8c16560cd09d

talk/app/webrtc/java/jni/androidmediadecoder_jni.h

@@ -51,7 +51,7 @@ class MediaCodecVideoDecoderFactory
   static jobject render_egl_context_;
 
  private:
-  bool is_platform_supported_;
+  std::vector<webrtc::VideoCodecType> supported_codec_types_;
 };
 
 }  // namespace webrtc_jni