Encrypted Media: Add config change support in DecryptingVideoDecoder.

media/filters/decrypting_video_decoder.h

Index: media/filters/decrypting_video_decoder.h
diff --git a/media/filters/decrypting_video_decoder.h b/media/filters/decrypting_video_decoder.h
index fd856a6a8f83ffeb659fef4c1cc0bc379495bd3c..9da57a143620330015fe008a1c36a2b5e327f897 100644
--- a/media/filters/decrypting_video_decoder.h
+++ b/media/filters/decrypting_video_decoder.h
@@ -55,6 +55,7 @@ class MEDIA_EXPORT DecryptingVideoDecoder : public VideoDecoder {
     kDecryptorRequested,
     kPendingDecoderInit,
     kIdle,
+    kPendingConfigChange,
     kPendingDemuxerRead,
     kPendingDecode,
     kWaitingForKey,
@@ -65,9 +66,12 @@ class MEDIA_EXPORT DecryptingVideoDecoder : public VideoDecoder {
   // Callback for DecryptorHost::RequestDecryptor().
   void SetDecryptor(Decryptor* decryptor);
 
-  // Callback for Decryptor::InitializeVideoDecoder().
+  // Callback for Decryptor::InitializeVideoDecoder() during initialization.
   void FinishInitialization(bool success);
 
+  // Callback for Decryptor::InitializeVideoDecoder() during config change.
+  void FinishConfigChange(bool success);
+
   void ReadFromDemuxerStream();
 
   // Callback for DemuxerStream::Read().