Change call-sites now that SkCanvas is not ref-counted

ui/surface/transport_dib.h

 // Copyright (c) 2012 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 UI_SURFACE_TRANSPORT_DIB_H_
 #define UI_SURFACE_TRANSPORT_DIB_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 53 matching lines @@
   // pointer will be owned by the caller. The bitmap will be of the given size,
   // which should fit inside this memory. Bitmaps returned will be either
   // opaque or have premultiplied alpha.
   //
   // On POSIX, this |TransportDIB| will be mapped if not already. On Windows,
   // this |TransportDIB| will NOT be mapped and should not be mapped prior,
   // because PlatformCanvas will map the file internally.
   //
   // Will return NULL on allocation failure. This could be because the image
   // is too large to map into the current process' address space.
-  SkCanvas* GetPlatformCanvas(int w, int h, bool opaque);
+  std::unique_ptr<SkCanvas> GetPlatformCanvas(int w, int h, bool opaque);
 
   // Map the DIB into the current process if it is not already. This is used to
   // map a DIB that has already been created. Returns true if the DIB is mapped.
   bool Map();
 
   // Return a pointer to the shared memory.
   void* memory() const;
 
   // Return the maximum size of the shared memory. This is not the amount of
   // data which is valid, you have to know that via other means, this is simply
@@ skipping 11 matching lines @@
 
   explicit TransportDIB(base::SharedMemoryHandle dib);
   base::SharedMemory shared_memory_;
   uint32_t sequence_num_;
   size_t size_;  // length, in bytes
 
   DISALLOW_COPY_AND_ASSIGN(TransportDIB);
 };
 
 #endif  // UI_SURFACE_TRANSPORT_DIB_H_