Add initialization callback support for Video Decoder PPAPI.

media/video/video_decode_accelerator.h

Index: media/video/video_decode_accelerator.h
diff --git a/media/video/video_decode_accelerator.h b/media/video/video_decode_accelerator.h
index 807f9232fae7a00eeb7db587668b6fd000dd18e9..807501fb124f8c8febf64c0e532baf4ca3d7fecd 100644
--- a/media/video/video_decode_accelerator.h
+++ b/media/video/video_decode_accelerator.h
@@ -186,6 +186,9 @@ class VideoDecodeAccelerator {
    public:
     virtual ~Client() {}
 
+    // Callback to notify client that decoder has been initialized.
+    virtual void NotifyInitializeDone() = 0;
+
     // Callback to tell the information needed by the client to provide decoding
     // buffer to the decoder.
     virtual void ProvidePictureBuffers(