Fix MSE GC, make it less aggressive, more spec-compliant (Blink CL)

Source/modules/mediasource/SourceBuffer.h

 /*
  * Copyright (C) 2013 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 96 matching lines @@
     // Oilpan: eagerly release owned m_webSourceBuffer
     EAGERLY_FINALIZE();
     DECLARE_VIRTUAL_TRACE();
 
 private:
     SourceBuffer(PassOwnPtr<WebSourceBuffer>, MediaSource*, GenericEventQueue*);
 
     bool isRemoved() const;
     void scheduleEvent(const AtomicString& eventName);
 
+    bool prepareAppend(size_t newDataSize, ExceptionState&);
+    bool evictCodedFrames(size_t newDataSize);
     void appendBufferInternal(const unsigned char*, unsigned, ExceptionState&);
     void appendBufferAsyncPart();
+    void appendError(bool decodeError);
 
     void removeAsyncPart();
 
     void appendStreamInternal(Stream*, ExceptionState&);
     void appendStreamAsyncPart();
     void appendStreamDone(bool success);
     void clearAppendStreamState();
 
     // FileReaderLoaderClient interface
     void didStartLoading() override;
@@ skipping 24 matching lines @@
     bool m_streamMaxSizeValid;
     unsigned long long m_streamMaxSize;
     AsyncMethodRunner<SourceBuffer> m_appendStreamAsyncPartRunner;
     Member<Stream> m_stream;
     OwnPtr<FileReaderLoader> m_loader;
 };
 
 } // namespace blink
 
 #endif // SourceBuffer_h