Refactor WritableBuffer interface for more useful ptr management.

media/base/buffers.h

 // Copyright (c) 2008-2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Defines various types of timestamped media buffers used for transporting
 // data between filters.  Every buffer contains a timestamp in microseconds
 // describing the relative position of the buffer within the media stream, and
 // the duration in microseconds for the length of time the buffer will be
 // rendered.
 //
@@ skipping 84 matching lines @@
   // Returns the size of valid data in bytes.
   virtual size_t GetDataSize() const = 0;
 
   // If there's no data in this buffer, it represents end of stream.
   virtual bool IsEndOfStream() const { return GetData() == NULL; }
 };
 
 
 class WritableBuffer : public Buffer  {
  public:
-  // Returns a read-write pointer to the buffer data.  When this method is
-  // called, any pointers previously returned from this method are invalid, and
-  // any data previously written to the buffer is invalid.  The buffer size
-  // is guaranteed to be at least the size of |buffer_size|.  The size
-  // that the GetDataSize() method will return is set to |buffer_size|.
-  // If, after filling the buffer, the caller wants to set the size to a smaller
-  // value then they can call the SetDataSize() method.
-  virtual uint8* GetWritableData(size_t buffer_size) = 0;
+  // Returns a read-write pointer to the buffer data.
+  virtual uint8* GetWritableData() = 0;
 
   // Updates the size of valid data in bytes, which must be less than or equal
-  // to the |buffer_size| passed to GetWritableData().
+  // to GetBufferSize().
   virtual void SetDataSize(size_t data_size) = 0;
+
+  // Returns the size of the underlying buffer.
+  virtual size_t GetBufferSize() const = 0;
 };
 
 
 struct VideoSurface {
   static const size_t kMaxPlanes = 3;
 
   static const size_t kNumRGBPlanes = 1;
   static const size_t kRGBPlane = 0;
 
   static const size_t kNumYUVPlanes = 3;
@@ skipping 47 matching lines @@
   // Unlocks the underlying surface, the VideoSurface acquired from Lock is no
   // longer guaranteed to be valid.
   virtual void Unlock() = 0;
 
   virtual bool IsEndOfStream() const = 0;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_BUFFERS_H_