Make all scrollable layers visible to hit testing.

cc/trees/layer_tree_impl.cc

Index: cc/trees/layer_tree_impl.cc
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index 1aad8e4acf9d0c2508c00c8a2f560735be0f0d1c..edfd5b0aeeea09e74d7d92ef3d91362070fd3ba4 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -1887,16 +1887,15 @@ static void FindClosestMatchingLayer(const gfx::PointF& screen_space_point,
   }
 }
 
-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);
   }
 };
 
@@ -1913,7 +1912,7 @@ LayerTreeImpl::FindFirstScrollingLayerOrScrollbarLayerThatIsHitByPoint(
 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();
   }
 };