Feed ScrollableArea::showOverlayScrollbars into ScrollbarAnimationController.

cc/input/scrollbar_animation_controller.cc

 // Copyright 2014 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/scrollbar_animation_controller.h"
 
 #include <algorithm>
 
 #include "base/time/time.h"
 #include "cc/trees/layer_tree_impl.h"
@@ skipping 207 matching lines @@
     vertical_controller_->UpdateThumbThicknessScale();
     horizontal_controller_->UpdateThumbThicknessScale();
   }
 }
 
 void ScrollbarAnimationController::WillUpdateScroll() {
   if (show_scrollbars_on_scroll_gesture_)
     DidScrollUpdate();
 }
 
+void ScrollbarAnimationController::DidRequestShowFromMainThread() {
+  DidScrollUpdate();
+}
+
 void ScrollbarAnimationController::DidResize() {
   StopAnimation();
   Show();
 
   // As an optimization, we avoid spamming fade delay tasks during active fast
   // scrolls.
   if (!currently_scrolling_) {
     PostDelayedFadeOut(true);
   } else {
     show_in_fast_scroll_ = true;
@@ skipping 151 matching lines @@
   if (opacity_ != opacity)
     client_->SetNeedsRedrawForScrollbarAnimation();
 
   opacity_ = opacity;
 
   if (previouslyVisible != currentlyVisible)
     client_->DidChangeScrollbarVisibility();
 }
 
 }  // namespace cc