Optionally clear PlatformCanvas instances.

content/browser/renderer_host/backing_store_gtk.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 "content/browser/renderer_host/backing_store_gtk.h"
 
 #include <cairo-xlib.h>
 #include <gtk/gtk.h>
 #include <stdlib.h>
 #include <sys/ipc.h>
@@ skipping 529 matching lines @@
   } else {
     // Non-shared memory case just copy the image from the server.
     image = XGetImage(display_, pixmap_,
                       rect.x(), rect.y(), width, height,
                       AllPlanes, ZPixmap);
   }
 
   // TODO(jhawkins): Need to convert the image data if the image bits per pixel
   // is not 32.
   // Note that this also initializes the output bitmap as opaque.
-  if (!output->initialize(width, height, true) ||
+  if (!output->initialize(width, height, skia::PlatformDevice::FLAGS_OPAQUE) ||
       image->bits_per_pixel != 32) {
     if (shared_memory_support_ != ui::SHARED_MEMORY_NONE)
       DestroySharedImage(display_, image, &shminfo);
     else
       XDestroyImage(image);
     return false;
   }
 
   // The X image might have a different row stride, so iterate through
   // it and copy each row out, only up to the pixels we're actually
@@ skipping 92 matching lines @@
   cairo_set_source(cr, pattern);
   cairo_pattern_destroy(pattern);
 
   cairo_identity_matrix(cr);
 
   cairo_rectangle(cr, rect.x(), rect.y(), rect.width(), rect.height());
   cairo_fill(cr);
   cairo_destroy(cr);
 }
 #endif