remove legacy code from PlatformCanvas days

chrome/browser/thumbnails/content_based_thumbnailing_algorithm.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 "chrome/browser/thumbnails/content_based_thumbnailing_algorithm.h"
 
 #include <stddef.h>
 
 #include "base/metrics/histogram_macros.h"
 #include "base/task_scheduler/post_task.h"
@@ skipping 115 matching lines @@
     // This means that the source bitmap has been requested and at least
     // clipped. Upstream code in same cases seems opportunistic and it may
     // not perform actual resizing if copying with resize is not supported.
     // In this case we will resize to the orignally requested copy size.
     resize_target = context->requested_copy_size;
     clipped_bitmap = received_bitmap;
   }
 
   SkBitmap result_bitmap = SkBitmapOperations::DownsampleByTwoUntilSize(
       clipped_bitmap, resize_target.width(), resize_target.height());
-#if !defined(USE_AURA)
-  // If the bitmap has not been indeed resized, it has to be copied. In that
-  // case resampler simply returns a reference to the original bitmap, sitting
-  // in PlatformCanvas. One does not simply assign these 'magic' bitmaps to
-  // SkBitmap. They cannot be refcounted.
-  //
-  // With Aura, this does not happen since PlatformCanvas is platform
-  // idependent.
-  if (clipped_bitmap.width() == result_bitmap.width() &&
-      clipped_bitmap.height() == result_bitmap.height()) {
-    clipped_bitmap.copyTo(&result_bitmap, kN32_SkColorType);
-  }
-#endif
 
   return result_bitmap;
 }
 
 // static
 void ContentBasedThumbnailingAlgorithm::CreateRetargetedThumbnail(
     const SkBitmap& source_bitmap,
     const gfx::Size& thumbnail_size,
     scoped_refptr<ThumbnailingContext> context,
     const ConsumerCallback& callback) {
@@ skipping 73 matching lines @@
   } else {
     clipping_rect = gfx::Rect(source_size);
     target_size->SetSize(source_size.width() / 2, source_size.height() / 2);
     *clip_result = CLIP_RESULT_NOT_CLIPPED;
   }
 
   return clipping_rect;
 }
 
 }  // namespace thumbnails