remove legacy code from PlatformCanvas days

chrome/browser/thumbnails/simple_thumbnail_crop.cc

 // Copyright (c) 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 "chrome/browser/thumbnails/simple_thumbnail_crop.h"
 
 #include <algorithm>
 
 #include "base/metrics/histogram_macros.h"
 #include "content/public/browser/browser_thread.h"
@@ skipping 159 matching lines @@
     clipped_bitmap = GetClippedBitmap(
         bmp, desired_size.width(), desired_size.height(), clip_result);
   } else {
     clipped_bitmap = bitmap;
   }
 
   // Need to resize it to the size we want, so downsample until it's
   // close, and let the caller make it the exact size if desired.
   SkBitmap result = SkBitmapOperations::DownsampleByTwoUntilSize(
       clipped_bitmap, desired_size.width(), desired_size.height());
-#if !defined(USE_AURA)
-  // This is a bit subtle. SkBitmaps are refcounted, but the magic
-  // ones in PlatformCanvas can't be assigned to SkBitmap with proper
-  // refcounting.  If the bitmap doesn't change, then the downsampler
-  // will return the input bitmap, which will be the reference to the
-  // weird PlatformCanvas one insetad of a regular one. To get a
-  // regular refcounted bitmap, we need to copy it.
-  //
-  // On Aura, the PlatformCanvas is platform-independent and does not have
-  // any native platform resources that can't be refounted, so this issue does
-  // not occur.
-  //
-  // Note that GetClippedBitmap() does extractSubset() but it won't copy
-  // the pixels, hence we check result size == clipped_bitmap size here.
-  if (clipped_bitmap.width() == result.width() &&
-      clipped_bitmap.height() == result.height())
-    clipped_bitmap.copyTo(&result, kN32_SkColorType);
-#endif
 
   LOCAL_HISTOGRAM_TIMES(kThumbnailHistogramName,
                         base::TimeTicks::Now() - begin_compute_thumbnail);
   return result;
 }
 
 } // namespace thumbnails