Mac Chromium style checker cleanup

ui/gfx/image/image_mac_unittest.mm

 // 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 <Cocoa/Cocoa.h>
 
 #include "base/logging.h"
 #include "base/memory/scoped_nsobject.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/image/image.h"
@@ skipping 60 matching lines @@
   for (int i = 0; i < width * height * 3; ++i)
     image_rep_data[i] = 255;
 }
 
 class ImageMacTest : public testing::Test {
  public:
   ImageMacTest()
       : supported_scale_factors_(gfx::test::Get1xAnd2xScaleFactors()) {
   }
 
-  ~ImageMacTest() {
+  virtual ~ImageMacTest() {
   }
 
  private:
   ui::test::ScopedSetSupportedScaleFactors supported_scale_factors_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageMacTest);
 };
 
 namespace gt = gfx::test;
 
@@ skipping 112 matching lines @@
 
   // Convert to ImageSkia to check pixel contents of NSImageReps.
   gfx::ImageSkia image_skia = gfx::ImageSkiaFromNSImage(ns_image);
   EXPECT_TRUE(gt::IsEqual(bytes1x,
       image_skia.GetRepresentation(ui::SCALE_FACTOR_100P).sk_bitmap()));
   EXPECT_TRUE(gt::IsEqual(bytes2x,
       image_skia.GetRepresentation(ui::SCALE_FACTOR_200P).sk_bitmap()));
 }
 
 } // namespace