Merge Compositor's ScrollbarAnimationControllers into single class

content/renderer/gpu/render_widget_compositor.cc

Index: content/renderer/gpu/render_widget_compositor.cc
diff --git a/content/renderer/gpu/render_widget_compositor.cc b/content/renderer/gpu/render_widget_compositor.cc
index ae598c0253cc9674c4c93b2accfc9f45b6d54144..cd7e3a27aa075a4c73b5f6de6aad7fc73da2a98c 100644
--- a/content/renderer/gpu/render_widget_compositor.cc
+++ b/content/renderer/gpu/render_widget_compositor.cc
@@ -388,7 +388,7 @@ cc::LayerTreeSettings RenderWidgetCompositor::GenerateLayerTreeSettings(
     settings.scrollbar_animator = cc::LayerTreeSettings::NO_ANIMATOR;
     settings.solid_color_scrollbar_color = SK_ColorTRANSPARENT;
   } else {
-    settings.scrollbar_animator = cc::LayerTreeSettings::LINEAR_FADE;
+    settings.scrollbar_animator = cc::LayerTreeSettings::ANDROID;
     settings.scrollbar_fade_delay = base::TimeDelta::FromMilliseconds(300);
     settings.scrollbar_fade_resize_delay =
         base::TimeDelta::FromMilliseconds(2000);
@@ -427,7 +427,7 @@ cc::LayerTreeSettings RenderWidgetCompositor::GenerateLayerTreeSettings(
 #else  // defined(OS_ANDROID)
 #if !defined(OS_MACOSX)
   if (ui::IsOverlayScrollbarEnabled()) {
-    settings.scrollbar_animator = cc::LayerTreeSettings::THINNING;
+    settings.scrollbar_animator = cc::LayerTreeSettings::AURA_OVERLAY;
     settings.scrollbar_fade_delay = ui::kOverlayScrollbarFadeOutDelay;
     settings.scrollbar_fade_resize_delay =
         ui::kOverlayScrollbarFadeOutDelay;
@@ -438,7 +438,7 @@ cc::LayerTreeSettings RenderWidgetCompositor::GenerateLayerTreeSettings(
   } else {
     // TODO(bokan): This section is probably unneeded? We don't use scrollbar
     // animations for non overlay scrollbars.
-    settings.scrollbar_animator = cc::LayerTreeSettings::LINEAR_FADE;
+    settings.scrollbar_animator = cc::LayerTreeSettings::ANDROID;
     settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
     settings.scrollbar_fade_delay = base::TimeDelta::FromMilliseconds(500);
     settings.scrollbar_fade_resize_delay =