Do not skip subtrees with wheel or touch handlers

cc/trees/layer_tree_host_common.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_host_common.h"
 
 #include <algorithm>
 
 #include "base/debug/trace_event.h"
 #include "cc/base/math_util.h"
@@ skipping 469 matching lines @@
   // case where we may animate to a non-singular transform and wish to
   // pre-raster.
   if (!HasInvertibleOrAnimatedTransform(layer))
     return true;
 
   // When we need to do a readback/copy of a layer's output, we can not skip
   // it or any of its ancestors.
   if (layer->draw_properties().layer_or_descendant_has_copy_request)
     return false;
 
+  // We cannot skip the the subtree if a descendant has a wheel or touch handler
+  // or the hit testing code will break (it requires fresh transforms, etc).
+  if (layer->draw_properties().layer_or_descendant_has_handler)
+    return false;
+
   // If the layer is not drawn, then skip it and its subtree.
   if (!layer_is_drawn)
     return true;
 
   // If layer is on the pending tree and opacity is being animated then
   // this subtree can't be skipped as we need to create, prioritize and
   // include tiles for this layer when deciding if tree can be activated.
   if (layer->layer_tree_impl()->IsPendingTree() && layer->OpacityIsAnimating())
     return false;
 
   // The opacity of a layer always applies to its children (either implicitly
   // via a render surface or explicitly if the parent preserves 3D), so the
   // entire subtree can be skipped if this layer is fully transparent.
   return !layer->opacity();
 }
 
 static inline bool SubtreeShouldBeSkipped(Layer* layer, bool layer_is_drawn) {
   // If the layer transform is not invertible, it should not be drawn.
   if (!layer->transform_is_invertible() && !layer->TransformIsAnimating())
     return true;
 
   // When we need to do a readback/copy of a layer's output, we can not skip
   // it or any of its ancestors.
   if (layer->draw_properties().layer_or_descendant_has_copy_request)
     return false;
 
+  // We cannot skip the the subtree if a descendant has a wheel or touch handler
+  // or the hit testing code will break (it requires fresh transforms, etc).
+  if (layer->draw_properties().layer_or_descendant_has_handler)
+    return false;
+
   // If the layer is not drawn, then skip it and its subtree.
   if (!layer_is_drawn)
     return true;
 
   // If the opacity is being animated then the opacity on the main thread is
   // unreliable (since the impl thread may be using a different opacity), so it
   // should not be trusted.
   // In particular, it should not cause the subtree to be skipped.
   // Similarly, for layers that might animate opacity using an impl-only
   // animation, their subtree should also not be skipped.
@@ skipping 651 matching lines @@
   DCHECK_EQ(render_surface_layer_list->back(), layer_to_remove);
   MarkLayerListWithRenderSurfaceLayerListId(
       &layer_to_remove->render_surface()->layer_list(), 0);
   MarkLayerWithRenderSurfaceLayerListId(layer_to_remove, 0);
   render_surface_layer_list->pop_back();
   layer_to_remove->ClearRenderSurfaceLayerList();
 }
 
 struct PreCalculateMetaInformationRecursiveData {
   bool layer_or_descendant_has_copy_request;
+  bool layer_or_descendant_has_handler;
   int num_unclipped_descendants;
 
   PreCalculateMetaInformationRecursiveData()
       : layer_or_descendant_has_copy_request(false),
+        layer_or_descendant_has_handler(false),
         num_unclipped_descendants(0) {}
 
   void Merge(const PreCalculateMetaInformationRecursiveData& data) {
     layer_or_descendant_has_copy_request |=
         data.layer_or_descendant_has_copy_request;
+    layer_or_descendant_has_handler |= data.layer_or_descendant_has_handler;
     num_unclipped_descendants +=
         data.num_unclipped_descendants;
   }
 };
 
 // Recursively walks the layer tree to compute any information that is needed
 // before doing the main recursion.
 template <typename LayerType>
 static void PreCalculateMetaInformation(
     LayerType* layer,
@@ skipping 39 matching lines @@
 
   if (layer->clip_children()) {
     int num_clip_children = layer->clip_children()->size();
     DCHECK_GE(recursive_data->num_unclipped_descendants, num_clip_children);
     recursive_data->num_unclipped_descendants -= num_clip_children;
   }
 
   if (layer->HasCopyRequest())
     recursive_data->layer_or_descendant_has_copy_request = true;
 
+  if (!layer->touch_event_handler_region().IsEmpty() ||
+      layer->have_wheel_event_handlers())
+    recursive_data->layer_or_descendant_has_handler = true;
+
   layer->draw_properties().num_descendants_that_draw_content =
       num_descendants_that_draw_content;
   layer->draw_properties().num_unclipped_descendants =
       recursive_data->num_unclipped_descendants;
   layer->draw_properties().layer_or_descendant_has_copy_request =
       recursive_data->layer_or_descendant_has_copy_request;
+  layer->draw_properties().layer_or_descendant_has_handler =
+      recursive_data->layer_or_descendant_has_handler;
 }
 
 static void RoundTranslationComponents(gfx::Transform* transform) {
   transform->matrix().set(0, 3, MathUtil::Round(transform->matrix().get(0, 3)));
   transform->matrix().set(1, 3, MathUtil::Round(transform->matrix().get(1, 3)));
 }
 
 template <typename LayerType>
 struct SubtreeGlobals {
   LayerSorter* layer_sorter;
@@ skipping 1136 matching lines @@
       inputs->current_render_surface_layer_list_id);
 
   // The dummy layer list should not have been used.
   DCHECK_EQ(0u, dummy_layer_list.size());
   // A root layer render_surface should always exist after
   // CalculateDrawProperties.
   DCHECK(inputs->root_layer->render_surface());
 }
 
 }  // namespace cc