Make all scrollable layers visible to hit testing.

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 1869 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 ScrollsOrScrollbarAnyDrawnRenderSurfaceLayerListMember(
-    LayerImpl* layer) {
-  return layer->scrolls_drawn_descendant() ||
+static bool IsScrollableOrDrawnScrollbarLayer(LayerImpl* layer) {
+  return layer->scrollable() ||

[majidvp, 2016/11/14 17:21:11]

Should we also check for LayerImpl::user_scrollable here?

[skobes, 2016/11/14 17:46:33]

ComputeLayerScrollsDrawnDescendants was not concerned with user_scrollable().  I
think that's handled by the scroll bubbling machinery
(LayerTreeHostImpl::ComputeScrollDelta etc.)

          (layer->ToScrollbarLayer() &&
           layer->is_drawn_render_surface_layer_list_member());
 }
 
 struct FindScrollingLayerOrScrollbarLayerFunctor {
   bool operator()(LayerImpl* layer) const {
-    return ScrollsOrScrollbarAnyDrawnRenderSurfaceLayerListMember(layer);
+    return IsScrollableOrDrawnScrollbarLayer(layer);
   }
 };
 
 LayerImpl*
 LayerTreeImpl::FindFirstScrollingLayerOrScrollbarLayerThatIsHitByPoint(
     const gfx::PointF& screen_space_point) {
   FindClosestMatchingLayerState state;
   LayerImpl* root_layer = layer_list_.empty() ? nullptr : layer_list_[0];
   FindClosestMatchingLayer(screen_space_point, root_layer,
                            FindScrollingLayerOrScrollbarLayerFunctor(), &state);
   return state.closest_match;
 }
 
 struct HitTestVisibleScrollableOrTouchableFunctor {
   bool operator()(LayerImpl* layer) const {
     return layer->is_drawn_render_surface_layer_list_member() ||
-           ScrollsOrScrollbarAnyDrawnRenderSurfaceLayerListMember(layer) ||
+           IsScrollableOrDrawnScrollbarLayer(layer) ||
            !layer->touch_event_handler_region().IsEmpty();
   }
 };
 
 LayerImpl* LayerTreeImpl::FindLayerThatIsHitByPoint(
     const gfx::PointF& screen_space_point) {
   if (layer_list_.empty())
     return NULL;
   bool update_lcd_text = false;
   if (!UpdateDrawProperties(update_lcd_text))
@@ skipping 146 matching lines @@
 
 void LayerTreeImpl::ResetAllChangeTracking() {
   layers_that_should_push_properties_.clear();
   // Iterate over all layers, including masks.
   for (auto& layer : *layers_)
     layer->ResetChangeTracking();
   property_trees_.ResetAllChangeTracking();
 }
 
 }  // namespace cc