Add display-resolution caching to GPU IDC

cc/tiles/mipmap_util.cc

 // 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.
 
 #include "cc/tiles/mipmap_util.h"
 
 namespace cc {
 namespace {
 // Calculates the size of |axis_base_size| at the given |mip_level| using
 // OpenGL rounding rules.
@@ skipping 37 matching lines @@
       return current_mip_level;
     }
   }
 }
 
 SkSize MipMapUtil::GetScaleAdjustmentForLevel(const gfx::Size& src_size,
                                               int mip_level) {
   if (src_size.width() == 0 || src_size.height() == 0 || mip_level == -1)
     return SkSize::Make(-1, -1);
 
-  gfx::Size target_size(ScaleAxisToMipLevel(src_size.width(), mip_level),
-                        ScaleAxisToMipLevel(src_size.height(), mip_level));
+  gfx::Size target_size = GetSizeForLevel(src_size, mip_level);
 
   return SkSize::Make(
       static_cast<float>(target_size.width()) / src_size.width(),
       static_cast<float>(target_size.height()) / src_size.height());
 }
 
+gfx::Size MipMapUtil::GetSizeForLevel(const gfx::Size& src_size,
+                                      int mip_level) {
+  if (src_size.width() == 0 || src_size.height() == 0 || mip_level == -1)
+    return gfx::Size(-1, -1);
+
+  return gfx::Size(ScaleAxisToMipLevel(src_size.width(), mip_level),
+                   ScaleAxisToMipLevel(src_size.height(), mip_level));
+}
+
 SkSize MipMapUtil::GetScaleAdjustmentForSize(const gfx::Size& src_size,
                                              const gfx::Size& target_size) {
   int target_mip_level = GetLevelForSize(src_size, target_size);
   return GetScaleAdjustmentForLevel(src_size, target_mip_level);
 }
 
 }  // namespace cc