Revert of Pinch/Zoom Infrastructure & Plumbing CL

cc/animation/scrollbar_animation_controller_linear_fade.cc

Index: cc/animation/scrollbar_animation_controller_linear_fade.cc
diff --git a/cc/animation/scrollbar_animation_controller_linear_fade.cc b/cc/animation/scrollbar_animation_controller_linear_fade.cc
index 049b87396a51ec42d4f5fd3c8515996a3b428f2e..863959b84c27691f9afe1cca9628b399fc3b04e9 100644
--- a/cc/animation/scrollbar_animation_controller_linear_fade.cc
+++ b/cc/animation/scrollbar_animation_controller_linear_fade.cc
@@ -112,17 +112,15 @@
 
 void ScrollbarAnimationControllerLinearFade::ApplyOpacityToScrollbars(
     float opacity) {
-  if (!scroll_layer_->scrollbars())
-    return;
+  ScrollbarLayerImplBase* horizontal_scrollbar =
+      scroll_layer_->horizontal_scrollbar_layer();
+  if (horizontal_scrollbar)
+    horizontal_scrollbar->SetOpacity(opacity);
 
-  LayerImpl::ScrollbarSet* scrollbars = scroll_layer_->scrollbars();
-  for (LayerImpl::ScrollbarSet::iterator it = scrollbars->begin();
-       it != scrollbars->end();
-       ++it) {
-    ScrollbarLayerImplBase* scrollbar = *it;
-    if (scrollbar->is_overlay_scrollbar())
-      scrollbar->SetOpacity(opacity);
-  }
+  ScrollbarLayerImplBase* vertical_scrollbar =
+      scroll_layer_->vertical_scrollbar_layer();
+  if (vertical_scrollbar)
+    vertical_scrollbar->SetOpacity(opacity);
 }
 
 }  // namespace cc