Prepare for publishing MediaMetadataRetriever as public API

step one:
o replaced captureFrame with getFrameAtTime
o removed getMode

bug - 2433195

Change-Id: I38a8cecef29014692f0b08b8818326e3ebb40a12
diff --git a/media/libmediaplayerservice/MetadataRetrieverClient.h b/media/libmediaplayerservice/MetadataRetrieverClient.h
index 4aab94f..8b4c0c7 100644
--- a/media/libmediaplayerservice/MetadataRetrieverClient.h
+++ b/media/libmediaplayerservice/MetadataRetrieverClient.h
@@ -44,8 +44,7 @@
     virtual status_t                setDataSource(const char *url);
     virtual status_t                setDataSource(int fd, int64_t offset, int64_t length);
     virtual status_t                setMode(int mode);
-    virtual status_t                getMode(int* mode) const;
-    virtual sp<IMemory>             captureFrame();
+    virtual sp<IMemory>             getFrameAtTime(int64_t timeUs, int option);
     virtual sp<IMemory>             extractAlbumArt();
     virtual const char*             extractMetadata(int keyCode);