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

skia/ext/vector_canvas_unittest.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 "build/build_config.h"
 
 #if !defined(OS_WIN)
 #include <unistd.h>
 #endif
 
@@ skipping 374 matching lines @@
 
     parent::TearDown();
   }
 
   void Init(int size) {
     size_ = size;
     context_ = new Context();
     bitmap_ = new Bitmap(*context_, size_, size_);
     vcanvas_ = new VectorCanvas(VectorPlatformDeviceEmf::CreateDevice(
         size_, size_, true, context_->context()));
-    pcanvas_ = new PlatformCanvas(size_, size_, false);
+    pcanvas_ = CreatePlatformCanvas(size_, size_, false);
 
     // Clear white.
     vcanvas_->drawARGB(255, 255, 255, 255, SkXfermode::kSrc_Mode);
     pcanvas_->drawARGB(255, 255, 255, 255, SkXfermode::kSrc_Mode);
   }
 
   // Compares both canvas and returns the pixel difference in percentage between
   // both images. 0 on success and ]0, 100] on failure.
   double ProcessImage(const FilePath::StringType& filename) {
     std::wstring number(base::StringPrintf(L"%02d_", number_++));
@@ skipping 553 matching lines @@
     pcanvas_->rotate(67);
     vcanvas_->drawBitmap(bitmap, 20, -50, NULL);
     pcanvas_->drawBitmap(bitmap, 20, -50, NULL);
     EXPECT_EQ(0., ProcessImage(FILE_PATH_LITERAL("rotate")));
   }
 }
 
 #endif  // !defined(USE_AURA)
 
 }  // namespace skia