Mac: Don't repaint scrollbars every frame

cc/BUILD.gn

 # 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.
 
 import("//testing/test.gni")
 
 component("cc") {
   sources = [
     "animation/animation.cc",
     "animation/animation.h",
@@ skipping 746 matching lines @@
     "layers/io_surface_layer_impl_unittest.cc",
     "layers/layer_impl_unittest.cc",
     "layers/layer_iterator_unittest.cc",
     "layers/layer_position_constraint_unittest.cc",
     "layers/layer_proto_converter_unittest.cc",
     "layers/layer_unittest.cc",
     "layers/layer_utils_unittest.cc",
     "layers/nine_patch_layer_impl_unittest.cc",
     "layers/nine_patch_layer_unittest.cc",
     "layers/painted_scrollbar_layer_impl_unittest.cc",
+    "layers/painted_scrollbar_layer_unittest.cc",
     "layers/picture_image_layer_impl_unittest.cc",
     "layers/picture_image_layer_unittest.cc",
     "layers/picture_layer_impl_unittest.cc",
     "layers/picture_layer_unittest.cc",
     "layers/render_surface_impl_unittest.cc",
     "layers/render_surface_unittest.cc",
     "layers/scrollbar_layer_unittest.cc",
     "layers/solid_color_layer_impl_unittest.cc",
     "layers/solid_color_scrollbar_layer_impl_unittest.cc",
     "layers/surface_layer_impl_unittest.cc",
@@ skipping 163 matching lines @@
     "//ui/gl",
     "//ui/gl:test_support",
   ]
 
   if (is_android) {
     isolate_file = "cc_perftests.isolate"
   }
 }
 # When adding support for isolates, please have a look at run-time dependencies
 # in the cc_unittests_run target in cc_tests.gyp.