Optionally clear PlatformCanvas instances.

ui/gfx/surface/transport_dib_mac.cc

 // Copyright (c) 2011 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/gfx/surface/transport_dib.h"
 
 #include <unistd.h>
 #include <sys/stat.h>
 
 #include "base/eintr_wrapper.h"
@@ skipping 46 matching lines @@
 
 // static
 bool TransportDIB::is_valid_id(Id id) {
   return id != 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())))
+  if (!canvas->initialize(
+          w, h,
+          skia::PlatformDevice::FLAGS_OPAQUE |
+              skia::PlatformDevice::FLAGS_INITIALIZED,
+          reinterpret_cast<uint8_t*>(memory())))
     return NULL;
   return canvas.release();
 }
 
 bool TransportDIB::Map() {
   if (!is_valid_handle(handle()))
     return false;
   if (memory())
     return true;
 
@@ skipping 11 matching lines @@
   return shared_memory_.memory();
 }
 
 TransportDIB::Id TransportDIB::id() const {
   return shared_memory_.id();
 }
 
 TransportDIB::Handle TransportDIB::handle() const {
   return shared_memory_.handle();
 }