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

skia/ext/bitmap_platform_device_cairo.cc

 // Copyright 2013 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 "build/build_config.h"
 #include "skia/ext/bitmap_platform_device_cairo.h"
 #include "skia/ext/platform_canvas.h"
 
 #if defined(OS_OPENBSD)
 #include <cairo.h>
@@ skipping 148 matching lines @@
   // Tell cairo to flush anything it has pending.
   cairo_surface_flush(surface);
   // Tell Cairo that we (probably) modified (actually, will modify) its pixel
   // buffer directly.
   cairo_surface_mark_dirty(surface);
   return cairo_;
 }
 
 // PlatformCanvas impl
 
-SkCanvas* CreatePlatformCanvas(int width, int height, bool is_opaque,
-                               uint8_t* data, OnFailureType failureType) {
+std::unique_ptr<SkCanvas> CreatePlatformCanvas(int width,
+                                               int height,
+                                               bool is_opaque,
+                                               uint8_t* data,
+                                               OnFailureType failureType) {
   sk_sp<SkBaseDevice> dev(
       BitmapPlatformDevice::Create(width, height, is_opaque, data));
   return CreateCanvas(dev, failureType);
 }
 
 }  // namespace skia