Merge Compositor's ScrollbarAnimationControllers into single class

cc/layers/scrollbar_layer_unittest.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 <stddef.h>
 
 #include <unordered_map>
 
 #include "base/memory/ptr_util.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ skipping 85 matching lines @@
   int next_id_;
   int total_ui_resource_created_;
   int total_ui_resource_deleted_;
 };
 
 class ScrollbarLayerTest : public testing::Test {
  public:
   ScrollbarLayerTest() {
     layer_tree_settings_.single_thread_proxy_scheduler = false;
     layer_tree_settings_.use_zero_copy = true;
-    layer_tree_settings_.scrollbar_animator = LayerTreeSettings::LINEAR_FADE;
+    layer_tree_settings_.scrollbar_animator =
+        LayerTreeSettings::ANDROID_OVERLAY;
     layer_tree_settings_.scrollbar_fade_delay =
         base::TimeDelta::FromMilliseconds(20);
     layer_tree_settings_.scrollbar_fade_duration =
         base::TimeDelta::FromMilliseconds(20);
     layer_tree_settings_.verify_clip_tree_calculations = true;
 
     scrollbar_layer_id_ = -1;
 
     animation_host_ = AnimationHost::CreateForTesting(ThreadInstance::MAIN);
 
@@ skipping 1051 matching lines @@
   TestScale(gfx::Rect(1240, 0, 15, 1333), 2.7754839f);
   TestScale(gfx::Rect(1240, 0, 15, 677), 2.46677136f);
 
   // Horizontal Scrollbars.
   TestScale(gfx::Rect(0, 1240, 1333, 15), 2.7754839f);
   TestScale(gfx::Rect(0, 1240, 677, 15), 2.46677136f);
 }
 
 }  // namespace
 }  // namespace cc