Initial implementation of onbufferedamountlow

public/platform/WebRTCDataChannelHandlerClient.h

 /*
  * Copyright (C) 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:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 13 matching lines @@
 
 #ifndef WebRTCDataChannelHandlerClient_h
 #define WebRTCDataChannelHandlerClient_h
 
 #include "WebCommon.h"
 #include "WebPrivatePtr.h"
 #include "WebString.h"
 
 namespace blink {
 
-class WebRTCDataChannelHandlerClient {
+class BLINK_EXPORT WebRTCDataChannelHandlerClient {
 public:
     enum ReadyState {
         ReadyStateConnecting = 0,
         ReadyStateOpen = 1,
         ReadyStateClosing = 2,
         ReadyStateClosed = 3,
     };
 
     virtual ~WebRTCDataChannelHandlerClient() { }
 
     virtual void didChangeReadyState(ReadyState) = 0;
+    // TODO(bemasc): Make this pure virtual once Chromium unit tests are updated
+    virtual void didDecreaseBufferedAmount(unsigned) { };
     virtual void didReceiveStringData(const WebString&) = 0;
     virtual void didReceiveRawData(const char*, size_t) = 0;
     virtual void didDetectError() = 0;
 };
 
 } // namespace blink
 
 #endif // WebRTCDataChannelHandlerClient_h