Add display-resolution caching to GPU IDC

cc/tiles/mipmap_util.h

 // Copyright 2016 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.
 
 #ifndef CC_TILES_MIPMAP_UTIL_H_
 #define CC_TILES_MIPMAP_UTIL_H_
 
 #include "cc/base/cc_export.h"
 #include "third_party/skia/include/core/SkSize.h"
 #include "ui/gfx/skia_util.h"
 
 namespace cc {
 
 class CC_EXPORT MipMapUtil {
  public:
   // Determine the smallest mip level that is larger than |target_size|. Each
   // mip level corresponds to a power of two scale of the image - for instance,
   // level 0 is original size, level 1 is 2x smaller, level 2 is 4x smaller,
   // etc...
   // Returns -1 if |src_size| or |target_size| is invalid (any dimension is 0).
   static int GetLevelForSize(const gfx::Size& src_size,
                              const gfx::Size& target_size);
 
   // Determines the scale factor for the given |mip_level|. Returns (-1, -1) if
   // |src_size| is invalid (width/height <= 0), or if mip_level is invalid (==
   // -1).
   static SkSize GetScaleAdjustmentForLevel(const gfx::Size& src_size,
                                            int mip_level);
 
+  // Determine the size of the given |mip_level|. Returns (-1, -1) if
+  // |src_size| is invalid (width/height <= 0) or if mip-level is invalid (==
+  // -1).
+  static gfx::Size GetSizeForLevel(const gfx::Size& src_size, int mip_level);
+
   // Determines the scale factor for the smallest mip level that is larger than
   // |target_size|. Returns (-1, -1) if |src_size| or |target_size| is invalid
   // (width/height <= 0).
   static SkSize GetScaleAdjustmentForSize(const gfx::Size& src_size,
                                           const gfx::Size& target_size);
 };
 
 }  // namespace cc
 
 #endif  // CC_TILES_MIPMAP_UTIL_H_