Merge Compositor's ScrollbarAnimationControllers into single class

cc/input/single_scrollbar_animation_controller_thinning_unittest.cc

 // Copyright 2013 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/input/single_scrollbar_animation_controller_thinning.h"
 
 #include "cc/layers/solid_color_scrollbar_layer_impl.h"
 #include "cc/test/fake_impl_task_runner_provider.h"
 #include "cc/test/fake_layer_tree_host_impl.h"
 #include "cc/test/geometry_test_utils.h"
 #include "cc/test/test_task_graph_runner.h"
 #include "cc/trees/layer_tree_impl.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using testing::AtLeast;
 using testing::Mock;
 using testing::NiceMock;
 using testing::_;
 
 namespace cc {
 namespace {
 
-// These constants are hard-coded and should match the values in
-// single_scrollbar_animation_controller_thinning.cc.
-const float kIdleThicknessScale = 0.4f;
-const float kDefaultMouseMoveDistanceToTriggerAnimation = 25.f;
+const float kIdleThicknessScale =
+    SingleScrollbarAnimationControllerThinning::kIdleThicknessScale;
+const float kDefaultMouseMoveDistanceToTriggerAnimation =
+    SingleScrollbarAnimationControllerThinning::
+        kDefaultMouseMoveDistanceToTriggerAnimation;
 
 class MockSingleScrollbarAnimationControllerClient
     : public ScrollbarAnimationControllerClient {
  public:
   explicit MockSingleScrollbarAnimationControllerClient(
       LayerTreeHostImpl* host_impl)
       : host_impl_(host_impl) {}
   virtual ~MockSingleScrollbarAnimationControllerClient() {}
 
   ScrollbarSet ScrollbarsFor(int scroll_layer_id) const override {
@@ skipping 334 matching lines @@
                   scrollbar_layer_->thumb_thickness_scale_factor());
 
   time += kThinningDuration / 2;
   scrollbar_controller_->Animate(time);
   EXPECT_FLOAT_EQ(kIdleThicknessScale,
                   scrollbar_layer_->thumb_thickness_scale_factor());
 }
 
 }  // namespace
 }  // namespace cc