Add a cache of LayerImpl's viewport layer type

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 121 matching lines @@
 }
 
 void LayerTreeImpl::RecreateTileResources() {
   if (!LayerListIsEmpty()) {
     LayerTreeHostCommon::CallFunctionForEveryLayer(
         this, [](LayerImpl* layer) { layer->RecreateTileResources(); });
   }
 }
 
 bool LayerTreeImpl::IsViewportLayerId(int id) const {
-  if (id == inner_viewport_scroll_layer_id_ ||
-      id == outer_viewport_scroll_layer_id_)
-    return true;
+#if DCHECK_IS_ON()
+  // Ensure the LayerImpl viewport layer types correspond to the LayerTreeImpl's
+  // viewport layers.
+  if (id == inner_viewport_scroll_layer_id_)
+    DCHECK(LayerById(id)->viewport_layer_type() == INNER_VIEWPORT_SCROLL);
+  if (id == outer_viewport_scroll_layer_id_)
+    DCHECK(LayerById(id)->viewport_layer_type() == OUTER_VIEWPORT_SCROLL);
   if (InnerViewportContainerLayer() &&
       id == InnerViewportContainerLayer()->id())
-    return true;
+    DCHECK(InnerViewportContainerLayer()->viewport_layer_type() ==
+           INNER_VIEWPORT_CONTAINER);
   if (OuterViewportContainerLayer() &&
       id == OuterViewportContainerLayer()->id())
-    return true;
-
+    DCHECK(OuterViewportContainerLayer()->viewport_layer_type() ==
+           OUTER_VIEWPORT_CONTAINER);
+#endif
+  if (auto* layer = LayerById(id))
+    return layer->viewport_layer_type() != NOT_VIEWPORT_LAYER;
   return false;
 }
 
 void LayerTreeImpl::DidUpdateScrollOffset(int layer_id) {
   DidUpdateScrollState(layer_id);
   TransformTree& transform_tree = property_trees()->transform_tree;
   ScrollTree& scroll_tree = property_trees()->scroll_tree;
   int transform_id = TransformTree::kInvalidNodeId;
 
   // If pending tree topology changed and we still want to notify the pending
@@ skipping 241 matching lines @@
 
   target_tree->PassSwapPromises(std::move(swap_promise_list_));
   swap_promise_list_.clear();
 
   target_tree->set_browser_controls_shrink_blink_size(
       browser_controls_shrink_blink_size_);
   target_tree->set_top_controls_height(top_controls_height_);
   target_tree->set_bottom_controls_height(bottom_controls_height_);
   target_tree->PushBrowserControls(nullptr);
 
+  // The page scale factor update can affect scrolling which requires that
+  // these ids are set, so this must be before PushPageScaleFactorAndLimits.
+  target_tree->SetViewportLayersFromIds(
+      overscroll_elasticity_layer_id_, page_scale_layer_id_,
+      inner_viewport_scroll_layer_id_, outer_viewport_scroll_layer_id_);
+
   // Active tree already shares the page_scale_factor object with pending
   // tree so only the limits need to be provided.
   target_tree->PushPageScaleFactorAndLimits(nullptr, min_page_scale_factor(),
                                             max_page_scale_factor());
   target_tree->SetDeviceScaleFactor(device_scale_factor());
   target_tree->set_painted_device_scale_factor(painted_device_scale_factor());
   target_tree->SetRasterColorSpace(raster_color_space_);
   target_tree->elastic_overscroll()->PushPendingToActive();
 
   target_tree->set_content_source_id(content_source_id());
 
   target_tree->set_local_surface_id(local_surface_id());
 
   target_tree->pending_page_scale_animation_ =
       std::move(pending_page_scale_animation_);
 
-  target_tree->SetViewportLayersFromIds(
-      overscroll_elasticity_layer_id_, page_scale_layer_id_,
-      inner_viewport_scroll_layer_id_, outer_viewport_scroll_layer_id_);
-
   target_tree->RegisterSelection(selection_);
 
   // This should match the property synchronization in
   // LayerTreeHost::finishCommitOnImplThread().
   target_tree->set_source_frame_number(source_frame_number());
   target_tree->set_background_color(background_color());
   target_tree->set_has_transparent_background(has_transparent_background());
   target_tree->set_have_scroll_event_handlers(have_scroll_event_handlers());
   target_tree->set_event_listener_properties(
       EventListenerClass::kTouchStartOrMove,
@@ skipping 524 matching lines @@
 
 void LayerTreeImpl::SetViewportLayersFromIds(
     int overscroll_elasticity_layer_id,
     int page_scale_layer_id,
     int inner_viewport_scroll_layer_id,
     int outer_viewport_scroll_layer_id) {
   overscroll_elasticity_layer_id_ = overscroll_elasticity_layer_id;
   page_scale_layer_id_ = page_scale_layer_id;
   inner_viewport_scroll_layer_id_ = inner_viewport_scroll_layer_id;
   outer_viewport_scroll_layer_id_ = outer_viewport_scroll_layer_id;
+
+  UpdateViewportLayerTypes();
 }
 
 void LayerTreeImpl::ClearViewportLayers() {
-  overscroll_elasticity_layer_id_ = Layer::INVALID_ID;
-  page_scale_layer_id_ = Layer::INVALID_ID;
-  inner_viewport_scroll_layer_id_ = Layer::INVALID_ID;
-  outer_viewport_scroll_layer_id_ = Layer::INVALID_ID;
+  SetViewportLayersFromIds(Layer::INVALID_ID, Layer::INVALID_ID,
+                           Layer::INVALID_ID, Layer::INVALID_ID);
+}
+
+void LayerTreeImpl::UpdateViewportLayerTypes() {
+  if (auto* inner_scroll = LayerById(inner_viewport_scroll_layer_id_)) {
+    inner_scroll->SetViewportLayerType(INNER_VIEWPORT_SCROLL);
+    if (auto* inner_container = inner_scroll->scroll_clip_layer())
+      inner_container->SetViewportLayerType(INNER_VIEWPORT_CONTAINER);
+  }
+  if (auto* outer_scroll = LayerById(outer_viewport_scroll_layer_id_)) {
+    outer_scroll->SetViewportLayerType(OUTER_VIEWPORT_SCROLL);
+    if (auto* outer_container = outer_scroll->scroll_clip_layer())
+      outer_container->SetViewportLayerType(OUTER_VIEWPORT_CONTAINER);
+  }
 }
 
 // For unit tests, we use the layer's id as its element id.
 static void SetElementIdForTesting(LayerImpl* layer) {
   layer->SetElementId(LayerIdToElementIdForTesting(layer->id()));
 }
 
 void LayerTreeImpl::SetElementIdsForTesting() {
   LayerListIterator<LayerImpl> it(root_layer_for_testing_);
   for (; it != LayerListIterator<LayerImpl>(nullptr); ++it) {
@@ skipping 1089 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