Simplify platform_canvas.h by recognizing that PlatformCanvas does not actually extend

ui/surface/transport_dib_android.cc

 // 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.
 
 #include "ui/surface/transport_dib.h"
 
 #include <sys/stat.h>
 #include <unistd.h>
 
 #include "base/eintr_wrapper.h"
@@ skipping 47 matching lines @@
 
 // static
 bool TransportDIB::is_valid_id(Id id) {
   // Same as is_valid_handle().
   return id.fd >= 0;
 }
 
 skia::PlatformCanvas* TransportDIB::GetPlatformCanvas(int w, int h) {
   if (!memory() && !Map())
     return NULL;
-  scoped_ptr<skia::PlatformCanvas> canvas(new skia::PlatformCanvas);
-  if (!canvas->initialize(w, h, true, reinterpret_cast<uint8_t*>(memory()))) {
-    // TODO(husky): Remove when http://b/issue?id=4233182 is definitely fixed.
-    LOG(ERROR) << "Failed to initialize canvas of size " << w << "x" << h;
-    return NULL;
-  }
-  return canvas.release();
+  return skia::CreatePlatformCanvas(w, h, true,
+                                    reinterpret_cast<uint8_t*>(memory()),
+                                    skia::RETURN_NULL_ON_FAILURE);
 }
 
 bool TransportDIB::Map() {
   if (!is_valid_handle(handle()))
     return false;
   // We will use ashmem_get_size_region() to figure out the size in Map(size).
   if (!shared_memory_.Map(0))
     return false;
 
   // TODO: Note that using created_size() below is a hack. See the comment in
   // SharedMemory::Map().
   size_ = shared_memory_.created_size();
   return true;
 }
 
 void* TransportDIB::memory() const {
   return shared_memory_.memory();
 }
 
 TransportDIB::Id TransportDIB::id() const {
   // Use FileDescriptor as id.
   return shared_memory_.handle();
 }
 
 TransportDIB::Handle TransportDIB::handle() const {
   return shared_memory_.handle();
 }