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}

sdk/android/src/java/org/webrtc/AndroidVideoTrackSourceObserver.java

@@ -11,6 +11,7 @@
 package org.webrtc;
 
 /** An implementation of CapturerObserver that forwards all calls from Java to the C layer. */
+@JNINamespace("webrtc::jni")
 class AndroidVideoTrackSourceObserver implements VideoCapturer.CapturerObserver {
   // Pointer to VideoTrackSourceProxy proxying AndroidVideoTrackSource.
   private final long nativeSource;
@@ -49,12 +50,12 @@ class AndroidVideoTrackSourceObserver implements VideoCapturer.CapturerObserver
         frame.getRotation(), frame.getTimestampNs(), frame.getBuffer());
   }
 
-  private native void nativeCapturerStarted(long nativeSource, boolean success);
-  private native void nativeCapturerStopped(long nativeSource);
-  private native void nativeOnByteBufferFrameCaptured(long nativeSource, byte[] data, int length,
-      int width, int height, int rotation, long timeStamp);
-  private native void nativeOnTextureFrameCaptured(long nativeSource, int width, int height,
+  private static native void nativeCapturerStarted(long source, boolean success);
+  private static native void nativeCapturerStopped(long source);
+  private static native void nativeOnByteBufferFrameCaptured(
+      long source, byte[] data, int length, int width, int height, int rotation, long timeStamp);
+  private static native void nativeOnTextureFrameCaptured(long source, int width, int height,
       int oesTextureId, float[] transformMatrix, int rotation, long timestamp);
-  private native void nativeOnFrameCaptured(long nativeSource, int width, int height, int rotation,
-      long timestampNs, VideoFrame.Buffer frame);
+  private static native void nativeOnFrameCaptured(
+      long source, int width, int height, int rotation, long timestampNs, VideoFrame.Buffer frame);
 }

sdk/android/src/java/org/webrtc/Histogram.java

@@ -19,6 +19,7 @@ package org.webrtc;
  *     Histogram.createCounts("WebRTC.Video.SomeMetric", 1, 10000, 50);
  * someMetricHistogram.addSample(someVariable);
  */
+@JNINamespace("webrtc::jni")
 class Histogram {
   private final long handle;
 

sdk/android/src/java/org/webrtc/JNINamespace.java

@@ -0,0 +1,26 @@
+/*
+ *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+package org.webrtc;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * @JNINamespace is used by the JNI generator to create the necessary JNI
+ * bindings and expose this method to native code using the specified namespace.
+ */
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface JNINamespace {
+  public String value();
+}

sdk/android/src/java/org/webrtc/JniCommon.java

@@ -13,11 +13,12 @@ package org.webrtc;
 import java.nio.ByteBuffer;
 
 /** Class with static JNI helper functions that are used in many places. */
+@JNINamespace("webrtc::jni")
 class JniCommon {
   /** Functions to increment/decrement an rtc::RefCountInterface pointer. */
-  static native void nativeAddRef(long nativeRefCountedPointer);
-  static native void nativeReleaseRef(long nativeRefCountedPointer);
+  static native void nativeAddRef(long refCountedPointer);
+  static native void nativeReleaseRef(long refCountedPointer);
 
-  public static native ByteBuffer allocateNativeByteBuffer(int size);
-  public static native void freeNativeByteBuffer(ByteBuffer buffer);
+  public static native ByteBuffer nativeAllocateByteBuffer(int size);
+  public static native void nativeFreeByteBuffer(ByteBuffer buffer);
 }

sdk/android/src/java/org/webrtc/NV12Buffer.java

@@ -12,6 +12,7 @@ package org.webrtc;
 
 import java.nio.ByteBuffer;
 
+@JNINamespace("webrtc::jni")
 public class NV12Buffer implements VideoFrame.Buffer {
   private final int width;
   private final int height;

sdk/android/src/java/org/webrtc/NV21Buffer.java

@@ -12,6 +12,7 @@ package org.webrtc;
 
 import java.nio.ByteBuffer;
 
+@JNINamespace("webrtc::jni")
 public class NV21Buffer implements VideoFrame.Buffer {
   private final byte[] data;
   private final int width;

sdk/android/src/java/org/webrtc/VP8Decoder.java

@@ -10,6 +10,12 @@
 
 package org.webrtc;
 
+@JNINamespace("webrtc::jni")
 class VP8Decoder extends WrappedNativeVideoDecoder {
-  @Override native long createNativeDecoder();
+  @Override
+  long createNativeDecoder() {
+    return nativeCreateDecoder();
+  }
+
+  static native long nativeCreateDecoder();
 }

sdk/android/src/java/org/webrtc/VP8Encoder.java

@@ -10,8 +10,14 @@
 
 package org.webrtc;
 
+@JNINamespace("webrtc::jni")
 class VP8Encoder extends WrappedNativeVideoEncoder {
-  @Override native long createNativeEncoder();
+  @Override
+  long createNativeEncoder() {
+    return nativeCreateEncoder();
+  }
+
+  static native long nativeCreateEncoder();
 
   @Override
   boolean isSoftwareEncoder() {

sdk/android/src/java/org/webrtc/VP9Decoder.java

@@ -10,8 +10,14 @@
 
 package org.webrtc;
 
+@JNINamespace("webrtc::jni")
 class VP9Decoder extends WrappedNativeVideoDecoder {
-  @Override native long createNativeDecoder();
+  @Override
+  long createNativeDecoder() {
+    return nativeCreateDecoder();
+  }
 
-  static native boolean isSupported();
+  static native long nativeCreateDecoder();
+
+  static native boolean nativeIsSupported();
 }

sdk/android/src/java/org/webrtc/VP9Encoder.java

@@ -10,13 +10,19 @@
 
 package org.webrtc;
 
+@JNINamespace("webrtc::jni")
 class VP9Encoder extends WrappedNativeVideoEncoder {
-  @Override native long createNativeEncoder();
+  @Override
+  long createNativeEncoder() {
+    return nativeCreateEncoder();
+  }
+
+  static native long nativeCreateEncoder();
 
   @Override
   boolean isSoftwareEncoder() {
     return true;
   }
 
-  static native boolean isSupported();
+  static native boolean nativeIsSupported();
 }