MediaCodec refactoring part 1-a: buffers become separate class

MediaCodecBuffer is meant to replace ABuffer and MediaBuffer in
communication between framework components. As the first step, replace
use of ABuffer in MediaCodec with MediaCodecBuffer, and adjust related
classes accordingly.

MediaCodec.getBuffer() and related APIs now returns MediaCodecBuffers;
thus change MediaCodec clients to use MediaCodecBuffer accordingly.

Test: manually tested for key use cases (Camera, YouTube and Play Movies)
Change-Id: Iba7ce131645e75ce5ddbf497fb793ab38b7f245b
diff --git a/media/jni/android_media_MediaCodec.h b/media/jni/android_media_MediaCodec.h
index c0c47ef..88b566a 100644
--- a/media/jni/android_media_MediaCodec.h
+++ b/media/jni/android_media_MediaCodec.h
@@ -146,8 +146,9 @@
 
     status_t mInitStatus;
 
+    template <typename T>
     status_t createByteBufferFromABuffer(
-            JNIEnv *env, bool readOnly, bool clearBuffer, const sp<ABuffer> &buffer,
+            JNIEnv *env, bool readOnly, bool clearBuffer, const sp<T> &buffer,
             jobject *buf) const;
 
     void cacheJavaObjects(JNIEnv *env);