Unhide the android.media.[Media]DataSource interface.

This allows apps to implement MediaDataSource, which is modeled on
stagefright's DataSource, to supply media data to the framework. This
was already implemented for MediaExtractor, but it was renamed from
DataSource.

MediaExtractor, MediaPlayer and MediaMetadataRetriever each have a new
overload: #setDataSource(android.media.MediaDataSource)

Only NuPlayer supports this new data source.

The change introduces:
 * IDataSource:        The binder interface for DataSource.
 * JMediaDataSource:   The native counterpart to the java interface. It
                       implements IDataSource.
 * CallbackDataSource: A stagefright DataSource that wraps an
                       IDataSource.

Change-Id: Ib3c944b49cc8a792c8eb9c85e5015c07f298ebc1
diff --git a/media/libmedia/mediametadataretriever.cpp b/media/libmedia/mediametadataretriever.cpp
index 873808a..9a76f58 100644
--- a/media/libmedia/mediametadataretriever.cpp
+++ b/media/libmedia/mediametadataretriever.cpp
@@ -129,6 +129,18 @@
     return mRetriever->setDataSource(fd, offset, length);
 }
 
+status_t MediaMetadataRetriever::setDataSource(
+    const sp<IDataSource>& dataSource)
+{
+    ALOGV("setDataSource(IDataSource)");
+    Mutex::Autolock _l(mLock);
+    if (mRetriever == 0) {
+        ALOGE("retriever is not initialized");
+        return INVALID_OPERATION;
+    }
+    return mRetriever->setDataSource(dataSource);
+}
+
 sp<IMemory> MediaMetadataRetriever::getFrameAtTime(int64_t timeUs, int option)
 {
     ALOGV("getFrameAtTime: time(%" PRId64 " us) option(%d)", timeUs, option);