Android: Use scoped java refs

We currently use raw jobject in our code mixed with sporadic
ScopedLocalRefFrame. This CL moves every jobject into a scoped object,
either local, global, or a parameter. Also, this CL uses the JNI
generation script to generate declaration stubs for the Java->C++
functions so that it no longer becomes possible to mistype them
without getting compilation errors.

TBR=brandt@webrtc.org

Bug: webrtc:8278,webrtc:6969
Change-Id: Ic7bac74a89c11180177d65041086d7db1cdfb516
Reviewed-on: https://webrtc-review.googlesource.com/34655
Commit-Queue: Magnus Jedvert <magjed@webrtc.org>
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21387}
diff --git a/sdk/android/api/org/webrtc/VideoDecoderFallback.java b/sdk/android/api/org/webrtc/VideoDecoderFallback.java
index 67e746f..f748da7 100644
--- a/sdk/android/api/org/webrtc/VideoDecoderFallback.java
+++ b/sdk/android/api/org/webrtc/VideoDecoderFallback.java
@@ -13,6 +13,7 @@
 /**
  * A combined video decoder that falls back on a secondary decoder if the primary decoder fails.
  */
+@JNINamespace("webrtc::jni")
 public class VideoDecoderFallback extends WrappedNativeVideoDecoder {
   private final VideoDecoder fallback;
   private final VideoDecoder primary;
@@ -24,8 +25,8 @@
 
   @Override
   long createNativeDecoder() {
-    return createNativeDecoder(fallback, primary);
+    return nativeCreateDecoder(fallback, primary);
   }
 
-  private static native long createNativeDecoder(VideoDecoder fallback, VideoDecoder primary);
+  private static native long nativeCreateDecoder(VideoDecoder fallback, VideoDecoder primary);
 }