Coverity: Fix leaking TransportDIB in GpuBackingStore{GLX,Win}::OnPaintToBackingStore

app/surface/transport_dib.h

 // Copyright (c) 2010 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.
 
 #ifndef APP_SURFACE_TRANSPORT_DIB_H_
 #define APP_SURFACE_TRANSPORT_DIB_H_
 
 #include "base/basictypes.h"
 
 #if defined(OS_WIN) || defined(OS_MACOSX)
@@ skipping 104 matching lines @@
   //
   // The size is the minimum size in bytes of the memory backing the transport
   // DIB (we may actually allocate more than that to give us better reuse when
   // cached).
   //
   // The sequence number is used to uniquely identify the transport DIB. It
   // should be unique for all transport DIBs ever created in the same
   // renderer.
   static TransportDIB* Create(size_t size, uint32 sequence_num);
 
-  // Map the referenced transport DIB. Returns NULL on failure.
+  // Map the referenced transport DIB.  The caller owns the returned object.
+  // Returns NULL on failure.
   static TransportDIB* Map(Handle transport_dib);
 
   // Returns true if the handle is valid.
   static bool is_valid(Handle dib);
 
   // Returns a canvas using the memory of this TransportDIB. The returned
   // pointer will be owned by the caller. The bitmap will be of the given size,
   // which should fit inside this memory.
   //
   // Will return NULL on allocation failure. This could be because the image
@@ skipping 35 matching lines @@
   Display* display_;  // connection to the X server
 #endif
   size_t size_;  // length, in bytes
 
   DISALLOW_COPY_AND_ASSIGN(TransportDIB);
 };
 
 class MessageLoop;
 
 #endif  // APP_SURFACE_TRANSPORT_DIB_H_