Revert of cc: Build Image to Region map during image meta-data generation.

cc/playback/display_item_list.cc

 // Copyright 2014 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 "cc/playback/display_item_list.h"
 
 #include <stddef.h>
 
 #include <string>
 
@@ skipping 253 matching lines @@
   Raster(generator.canvas(), nullptr, gfx::Rect(), 1.f);
 }
 
 void DisplayItemList::GetDiscardableImagesInRect(
     const gfx::Rect& rect,
     const gfx::SizeF& raster_scales,
     std::vector<DrawImage>* images) {
   image_map_.GetDiscardableImagesInRect(rect, raster_scales, images);
 }
 
-Region DisplayItemList::GetRegionForImage(uint32_t image_id) {
-  return image_map_.GetRegionForImage(image_id);
-}
-
 }  // namespace cc