cc: Scroll on main when possible incorrect hit testing hits scrollbar.

cc/trees/layer_tree_impl.cc

 // Copyright 2011 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/trees/layer_tree_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 1737 matching lines @@
         distance_to_intersection >
             state->closest_distance + std::numeric_limits<float>::epsilon();
 
     if (!state->closest_match || in_front_of_previous_candidate) {
       state->closest_distance = distance_to_intersection;
       state->closest_match = layer;
     }
   }
 }
 
-static bool ScrollsAnyDrawnRenderSurfaceLayerListMember(LayerImpl* layer) {
-  if (!layer->scrollable())
+static bool ScrollsOrScrollbarAnyDrawnRenderSurfaceLayerListMember(
+    LayerImpl* layer) {
+  if (!layer->scrollable() && !layer->ToScrollbarLayer())
     return false;
   if (layer->layer_or_descendant_is_drawn())
     return true;
 
   if (!layer->scroll_children())
     return false;
   for (std::set<LayerImpl*>::const_iterator it =
            layer->scroll_children()->begin();
        it != layer->scroll_children()->end(); ++it) {
     if ((*it)->layer_or_descendant_is_drawn())
       return true;
   }
   return false;
 }
 
-struct FindScrollingLayerFunctor {
+struct FindScrollingLayerOrScrollbarLayerFunctor {
   bool operator()(LayerImpl* layer) const {
-    return ScrollsAnyDrawnRenderSurfaceLayerListMember(layer);
+    return ScrollsOrScrollbarAnyDrawnRenderSurfaceLayerListMember(layer);
   }
 };
 
-LayerImpl* LayerTreeImpl::FindFirstScrollingLayerThatIsHitByPoint(
+LayerImpl*
+LayerTreeImpl::FindFirstScrollingLayerOrScrollbarLayerThatIsHitByPoint(
     const gfx::PointF& screen_space_point) {
   FindClosestMatchingLayerState state;
-  FindClosestMatchingLayer(
-      screen_space_point, root_layer(), FindScrollingLayerFunctor(),
-      property_trees_.transform_tree, property_trees_.clip_tree, &state);
+  FindClosestMatchingLayer(screen_space_point, root_layer(),
+                           FindScrollingLayerOrScrollbarLayerFunctor(),
+                           property_trees_.transform_tree,
+                           property_trees_.clip_tree, &state);
   return state.closest_match;
 }
 
 struct HitTestVisibleScrollableOrTouchableFunctor {
   bool operator()(LayerImpl* layer) const {
     return layer->IsDrawnRenderSurfaceLayerListMember() ||
-           ScrollsAnyDrawnRenderSurfaceLayerListMember(layer) ||
+           ScrollsOrScrollbarAnyDrawnRenderSurfaceLayerListMember(layer) ||
            !layer->touch_event_handler_region().IsEmpty();
   }
 };
 
 LayerImpl* LayerTreeImpl::FindLayerThatIsHitByPoint(
     const gfx::PointF& screen_space_point) {
   if (!root_layer())
     return NULL;
   bool update_lcd_text = false;
   if (!UpdateDrawProperties(update_lcd_text))
@@ skipping 298 matching lines @@
 }
 
 void LayerTreeImpl::ResetAllChangeTracking(PropertyTrees::ResetFlags flag) {
   layers_that_should_push_properties_.clear();
   for (auto* layer : *this)
     layer->ResetChangeTracking();
   property_trees_.ResetAllChangeTracking(flag);
 }
 
 }  // namespace cc