Merge Compositor's ScrollbarAnimationControllers into single class

cc/trees/layer_tree_impl.cc

Index: cc/trees/layer_tree_impl.cc
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index ca0f8587a82bc6c479ad0066a2876913db19e478..0c5e016199e785d3abc59aa91121d7c7569f42e1 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -24,8 +24,6 @@
 #include "cc/debug/traced_value.h"
 #include "cc/input/page_scale_animation.h"
 #include "cc/input/scrollbar_animation_controller.h"
-#include "cc/input/scrollbar_animation_controller_linear_fade.h"
-#include "cc/input/scrollbar_animation_controller_thinning.h"
 #include "cc/layers/heads_up_display_layer_impl.h"
 #include "cc/layers/layer.h"
 #include "cc/layers/layer_iterator.h"
@@ -1379,16 +1377,18 @@ LayerTreeImpl::CreateScrollbarAnimationController(int scroll_layer_id) {
   base::TimeDelta fade_duration = settings().scrollbar_fade_duration;
   switch (settings().scrollbar_animator) {
     case LayerTreeSettings::LINEAR_FADE: {

[chaopeng, 2017/02/15 19:59:50]

I agree change name to ScrollbarAnimationControllerOverlay vs
ScrollbarAnimationControllerAndroid would be better. But should we also change
the LayerTreeSettings?

[weiliangc, 2017/02/15 20:06:08]

Yeah sounds good. Make sure to comment there too.

-      return ScrollbarAnimationControllerLinearFade::Create(
-          scroll_layer_id, layer_tree_host_impl_, delay, resize_delay,
-          fade_duration);
+      return ScrollbarAnimationController::
+          CreateScrollbarAnimationControllerLinearFade(
+              scroll_layer_id, layer_tree_host_impl_, delay, resize_delay,
+              fade_duration);
     }
     case LayerTreeSettings::THINNING: {
       base::TimeDelta thinning_duration =
           settings().scrollbar_thinning_duration;
-      return ScrollbarAnimationControllerThinning::Create(
-          scroll_layer_id, layer_tree_host_impl_, delay, resize_delay,
-          fade_duration, thinning_duration);
+      return ScrollbarAnimationController::
+          CreateScrollbarAnimationControllerThinning(
+              scroll_layer_id, layer_tree_host_impl_, delay, resize_delay,
+              fade_duration, thinning_duration);
     }
     case LayerTreeSettings::NO_ANIMATOR:
       NOTREACHED();