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/include/media/IMediaMetadataRetriever.h b/include/media/IMediaMetadataRetriever.h
index 9baba8e..e517cf0 100644
--- a/include/media/IMediaMetadataRetriever.h
+++ b/include/media/IMediaMetadataRetriever.h
@@ -33,8 +33,7 @@
     virtual status_t        setDataSource(const char* srcUrl) = 0;
     virtual status_t        setDataSource(int fd, int64_t offset, int64_t length) = 0;
     virtual status_t        setMode(int mode) = 0;
-    virtual status_t        getMode(int* mode) const = 0;
-    virtual sp<IMemory>     captureFrame() = 0;
+    virtual sp<IMemory>     getFrameAtTime(int64_t timeUs, int option) = 0;
     virtual sp<IMemory>     extractAlbumArt() = 0;
     virtual const char*     extractMetadata(int keyCode) = 0;
 };