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/VideoEncoderFallback.java b/sdk/android/api/org/webrtc/VideoEncoderFallback.java
index 7894da9..59e7ffc 100644
--- a/sdk/android/api/org/webrtc/VideoEncoderFallback.java
+++ b/sdk/android/api/org/webrtc/VideoEncoderFallback.java
@@ -13,6 +13,7 @@
 /**
  * A combined video encoder that falls back on a secondary encoder if the primary encoder fails.
  */
+@JNINamespace("webrtc::jni")
 public class VideoEncoderFallback extends WrappedNativeVideoEncoder {
   private final VideoEncoder fallback;
   private final VideoEncoder primary;
@@ -24,7 +25,7 @@
 
   @Override
   long createNativeEncoder() {
-    return createNativeEncoder(fallback, primary);
+    return nativeCreateEncoder(fallback, primary);
   }
 
   @Override
@@ -32,5 +33,5 @@
     return isWrappedSoftwareEncoder(primary);
   }
 
-  private static native long createNativeEncoder(VideoEncoder fallback, VideoEncoder primary);
+  private static native long nativeCreateEncoder(VideoEncoder fallback, VideoEncoder primary);
 }