[WebSocket] bufferedAmount should not decrease inside a task.

Source/platform/network/SocketStreamHandleClient.h

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2009, 2011, 2012 Google Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 27 matching lines @@
 class SocketStreamError;
 class SocketStreamHandle;
 
 class SocketStreamHandleClient {
 public:
     virtual ~SocketStreamHandleClient() { }
 
     virtual void didOpenSocketStream(SocketStreamHandle*) { }
     virtual void didCloseSocketStream(SocketStreamHandle*) { }
     virtual void didReceiveSocketStreamData(SocketStreamHandle*, const char* /*data*/, int /*length*/) { }
-    virtual void didUpdateBufferedAmount(SocketStreamHandle*, size_t /*bufferedAmount*/) { }
+    virtual void didIncreaseBufferedAmount(SocketStreamHandle*, size_t amount) { }
+    virtual void didDecreaseBufferedAmount(SocketStreamHandle*, size_t amount) { }
 
     virtual void didFailSocketStream(SocketStreamHandle*, const SocketStreamError&) { }
 };
 
 } // namespace WebCore
 
 #endif // SocketStreamHandleClient_h