Android: Clean up JNI generated code

It's now possible to generate JNI code for constructors and enums
correctly. This CL cleans that up.

Bug: webrtc:8278,webrtc:8551,webrtc:8556
Change-Id: I2284a30139cbb186c80713eb6113eda5659c16ad
Reviewed-on: https://webrtc-review.googlesource.com/25622
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Commit-Queue: Magnus Jedvert <magjed@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20860}
diff --git a/sdk/android/api/org/webrtc/VideoFrame.java b/sdk/android/api/org/webrtc/VideoFrame.java
index 62d4cf2..3ee368d 100644
--- a/sdk/android/api/org/webrtc/VideoFrame.java
+++ b/sdk/android/api/org/webrtc/VideoFrame.java
@@ -121,6 +121,7 @@
   private final int rotation;
   private final long timestampNs;
 
+  @CalledByNative
   public VideoFrame(Buffer buffer, int rotation, long timestampNs) {
     if (buffer == null) {
       throw new IllegalArgumentException("buffer not allowed to be null");
@@ -206,12 +207,6 @@
     return newBuffer;
   }
 
-  // TODO(bugs.webrtc.org/8278): Add a way to generate JNI code for constructors directly.
-  @CalledByNative
-  static VideoFrame create(Buffer buffer, int rotation, long timestampNs) {
-    return new VideoFrame(buffer, rotation, timestampNs);
-  }
-
   private static native void cropAndScaleI420Native(ByteBuffer srcY, int srcStrideY,
       ByteBuffer srcU, int srcStrideU, ByteBuffer srcV, int srcStrideV, int cropX, int cropY,
       int cropWidth, int cropHeight, ByteBuffer dstY, int dstStrideY, ByteBuffer dstU,