Remove unused function in PictureLayerTiling

cc/resources/picture_layer_tiling.cc

 // Copyright 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 "cc/resources/picture_layer_tiling.h"
 
 #include <algorithm>
 #include <cmath>
 #include <limits>
 
@@ skipping 104 matching lines @@
     }
   }
 
   // Create a new tile because our twin didn't have a valid one.
   scoped_refptr<Tile> tile = client_->CreateTile(this, tile_rect);
   if (tile.get())
     tiles_[key] = tile;
   return tile.get();
 }
 
-Region PictureLayerTiling::OpaqueRegionInContentRect(
-    const gfx::Rect& content_rect) const {
-  Region opaque_region;
-  // TODO(enne): implement me
-  return opaque_region;
-}
-
 void PictureLayerTiling::SetCanUseLCDText(bool can_use_lcd_text) {
   for (TileMap::iterator it = tiles_.begin(); it != tiles_.end(); ++it)
     it->second->set_can_use_lcd_text(can_use_lcd_text);
 }
 
 void PictureLayerTiling::CreateMissingTilesInLiveTilesRect() {
   const PictureLayerTiling* twin_tiling = client_->GetTwinTiling(this);
   bool include_borders = true;
   for (TilingData::Iterator iter(
            &tiling_data_, live_tiles_rect_, include_borders);
@@ skipping 820 matching lines @@
   tiling_->UpdateEvictionCacheIfNeeded(tree_priority_);
   tile_iterator_ = tiling_->eviction_tiles_cache_.begin();
   is_valid_ = true;
   if (tile_iterator_ != tiling_->eviction_tiles_cache_.end() &&
       !(*tile_iterator_)->HasResources()) {
     ++(*this);
   }
 }
 
 }  // namespace cc