Reduce jank from favicon downscaling.

components/favicon_base/favicon_util.h

 // 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.
 
 #ifndef COMPONENTS_FAVICON_BASE_FAVICON_UTIL_H_
 #define COMPONENTS_FAVICON_BASE_FAVICON_UTIL_H_
 
 #include <vector>
 
 #include "components/favicon_base/favicon_types.h"
@@ skipping 18 matching lines @@
 void SetFaviconColorSpace(gfx::Image* image);
 
 // Takes a vector of PNG-encoded frames, and converts it to a gfx::Image of
 // size |favicon_size| in DIPS. The result gfx::Image has a gfx::ImageSkia with
 // gfx::ImageSkiaReps for each |favicon_scales|.
 gfx::Image SelectFaviconFramesFromPNGs(
     const std::vector<favicon_base::FaviconRawBitmapResult>& png_data,
     const std::vector<float>& favicon_scales,
     int favicon_size);
 
+// Generates a favicon_bitmap_result sized exactly to [desired_size,
+// desired_size] from the provided result set.  If the exact size is found in
+// the set, it just returns that; otherwise, it will decode the PNG, scale,
+// and encode a new PNG.
+favicon_base::FaviconRawBitmapResult ResizeFaviconBitmapResult(
+    const std::vector<favicon_base::FaviconRawBitmapResult>&
+        favicon_bitmap_results,
+    int desired_size_in_pixel);
+
 }  // namspace favicon_base
 
 #endif  // COMPONENTS_FAVICON_BASE_FAVICON_UTIL_H_