Android: Generate JNI code for remaining classes in sdk/android

Bug: webrtc:8278
Change-Id: I20a4388ab347d8745d0edde808f7a0b610f077f9
Reviewed-on: https://webrtc-review.googlesource.com/31484
Commit-Queue: Magnus Jedvert <magjed@webrtc.org>
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21227}

sdk/android/api/org/webrtc/VideoDecoderFactory.java

@@ -16,5 +16,5 @@ public interface VideoDecoderFactory {
    * Creates a VideoDecoder for the given codec. Supports the same codecs supported by
    * VideoEncoderFactory.
    */
-  public VideoDecoder createDecoder(String codecType);
+  @CalledByNative VideoDecoder createDecoder(String codecType);
 }