Android: Generate all C++ -> Java JNI code for VideoEncoder

The first example CL for generating JNI code
(https://webrtc-review.googlesource.com/c/src/+/4500) seems to stick, so
this CL updates the rest of the VideoEncoder. The JNI code for
Java -> C++ is still done manually.

This CL puts the necessary helper Java methods in a class called
VideoEncoderWrapper.

Bug: webrtc:8278
Change-Id: Ic3a6defe59c094f67ffd8ea86d6c272c676980ae
Reviewed-on: https://webrtc-review.googlesource.com/20871
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Commit-Queue: Magnus Jedvert <magjed@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20587}

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

@@ -0,0 +1,80 @@
+/*
+ *  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;
+
+// Explicit imports necessary for JNI generation.
+import org.webrtc.EncodedImage;
+import org.webrtc.VideoEncoder;
+import java.nio.ByteBuffer;
+
+/**
+ * This class contains the Java glue code for JNI generation of VideoEncoder.
+ */
+class VideoEncoderWrapper {
+  @CalledByNative
+  static VideoEncoder.Settings createSettings(int numberOfCores, int width, int height,
+      int startBitrate, int maxFramerate, boolean automaticResizeOn) {
+    return new VideoEncoder.Settings(
+        numberOfCores, width, height, startBitrate, maxFramerate, automaticResizeOn);
+  }
+
+  @CalledByNative
+  static VideoEncoder.EncodeInfo createEncodeInfo(EncodedImage.FrameType[] frameTypes) {
+    return new VideoEncoder.EncodeInfo(frameTypes);
+  }
+
+  @CalledByNative
+  static VideoEncoder.BitrateAllocation createBitrateAllocation(int[][] bitratesBbs) {
+    return new VideoEncoder.BitrateAllocation(bitratesBbs);
+  }
+
+  @CalledByNative
+  static EncodedImage.FrameType createFrameType(int nativeIndex) {
+    for (EncodedImage.FrameType type : EncodedImage.FrameType.values()) {
+      if (type.getNative() == nativeIndex) {
+        return type;
+      }
+    }
+    throw new IllegalArgumentException("Unknown native frame type: " + nativeIndex);
+  }
+
+  @CalledByNative
+  static boolean getScalingSettingsOn(VideoEncoder.ScalingSettings scalingSettings) {
+    return scalingSettings.on;
+  }
+
+  @CalledByNative
+  static Integer getScalingSettingsLow(VideoEncoder.ScalingSettings scalingSettings) {
+    return scalingSettings.low;
+  }
+
+  @CalledByNative
+  static Integer getScalingSettingsHigh(VideoEncoder.ScalingSettings scalingSettings) {
+    return scalingSettings.high;
+  }
+
+  @CalledByNative
+  static int getIntValue(Integer i) {
+    return i.intValue();
+  }
+
+  @CalledByNative
+  static VideoEncoder.Callback createEncoderCallback(final long nativeEncoder) {
+    return (EncodedImage frame, VideoEncoder.CodecSpecificInfo info)
+               -> onEncodedFrame(nativeEncoder, frame.buffer, frame.encodedWidth,
+                   frame.encodedHeight, frame.captureTimeNs, frame.frameType.getNative(),
+                   frame.rotation, frame.completeFrame, frame.qp);
+  }
+
+  private static native void onEncodedFrame(long nativeEncoder, ByteBuffer buffer, int encodedWidth,
+      int encodedHeight, long captureTimeNs, int frameType, int rotation, boolean completeFrame,
+      Integer qp);
+}