Add ScrollTree builder and unit test

cc/layers/layer.cc

 // Copyright 2010 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/layers/layer.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 46 matching lines @@
       layer_id_(g_next_layer_id.GetNext() + 1),
       ignore_set_needs_commit_(false),
       sorting_context_id_(0),
       parent_(nullptr),
       layer_tree_host_(nullptr),
       scroll_clip_layer_id_(INVALID_ID),
       num_descendants_that_draw_content_(0),
       transform_tree_index_(-1),
       effect_tree_index_(-1),
       clip_tree_index_(-1),
+      scroll_tree_index_(-1),
       property_tree_sequence_number_(-1),
       element_id_(0),
       mutable_properties_(kMutablePropertyNone),
       main_thread_scrolling_reasons_(
           MainThreadScrollingReason::kNotScrollingOnMain),
       should_flatten_transform_from_property_tree_(false),
       have_wheel_event_handlers_(false),
       have_scroll_event_handlers_(false),
       user_scrollable_horizontal_(true),
       user_scrollable_vertical_(true),
@@ skipping 1001 matching lines @@
 
 int Layer::effect_tree_index() const {
   if (!layer_tree_host_ ||
       layer_tree_host_->property_trees()->sequence_number !=
           property_tree_sequence_number_) {
     return -1;
   }
   return effect_tree_index_;
 }
 
+void Layer::SetScrollTreeIndex(int index) {
+  DCHECK(IsPropertyChangeAllowed());
+  if (scroll_tree_index_ == index)
+    return;
+  scroll_tree_index_ = index;
+  SetNeedsPushProperties();
+}
+
+int Layer::scroll_tree_index() const {
+  if (!layer_tree_host_ ||
+      layer_tree_host_->property_trees()->sequence_number !=
+          property_tree_sequence_number_) {
+    return -1;
+  }
+  return scroll_tree_index_;
+}
+
 void Layer::InvalidatePropertyTreesIndices() {
   int invalid_property_tree_index = -1;
   SetTransformTreeIndex(invalid_property_tree_index);
   SetClipTreeIndex(invalid_property_tree_index);
   SetEffectTreeIndex(invalid_property_tree_index);
 }
 
 void Layer::SetShouldFlattenTransform(bool should_flatten) {
   DCHECK(IsPropertyChangeAllowed());
   if (should_flatten_transform_ == should_flatten)
@@ skipping 93 matching lines @@
 #if defined(NDEBUG)
   if (frame_viewer_instrumentation::IsTracingLayerTreeSnapshots())
     layer->SetDebugInfo(TakeDebugInfo());
 #else
   layer->SetDebugInfo(TakeDebugInfo());
 #endif
 
   layer->SetTransformTreeIndex(transform_tree_index());
   layer->SetEffectTreeIndex(effect_tree_index());
   layer->SetClipTreeIndex(clip_tree_index());
+  layer->SetScrollTreeIndex(scroll_tree_index());
   layer->set_offset_to_transform_parent(offset_to_transform_parent_);
   layer->SetDoubleSided(double_sided_);
   layer->SetDrawsContent(DrawsContent());
   layer->SetHideLayerAndSubtree(hide_layer_and_subtree_);
   layer->SetHasRenderSurface(has_render_surface_);
   layer->SetForceRenderSurface(force_render_surface_);
   if (!layer->FilterIsAnimatingOnImplOnly() && !FilterIsAnimating())
     layer->SetFilters(filters_);
   DCHECK(!(FilterIsAnimating() && layer->FilterIsAnimatingOnImplOnly()));
   layer->SetBackgroundFilters(background_filters());
@@ skipping 251 matching lines @@
   Point3FToProto(transform_origin_, base->mutable_transform_origin());
   base->set_background_color(background_color_);
   SizeToProto(use_paint_properties ? paint_properties_.bounds : bounds_,
               base->mutable_bounds());
 
   // TODO(nyquist): Figure out what to do with debug info. See crbug.com/570372.
 
   base->set_transform_free_index(transform_tree_index_);
   base->set_effect_tree_index(effect_tree_index_);
   base->set_clip_tree_index(clip_tree_index_);
+  base->set_scroll_tree_index(scroll_tree_index_);
   Vector2dFToProto(offset_to_transform_parent_,
                    base->mutable_offset_to_transform_parent());
   base->set_double_sided(double_sided_);
   base->set_draws_content(draws_content_);
   base->set_hide_layer_and_subtree(hide_layer_and_subtree_);
   base->set_has_render_surface(has_render_surface_);
 
   // TODO(nyquist): Add support for serializing FilterOperations for
   // |filters_| and |background_filters_|. See crbug.com/541321.
 
@@ skipping 70 matching lines @@
   DCHECK(layer_tree_host_);
   const proto::BaseLayerProperties& base = proto.base();
 
   transform_origin_ = ProtoToPoint3F(base.transform_origin());
   background_color_ = base.background_color();
   bounds_ = ProtoToSize(base.bounds());
 
   transform_tree_index_ = base.transform_free_index();
   effect_tree_index_ = base.effect_tree_index();
   clip_tree_index_ = base.clip_tree_index();
+  scroll_tree_index_ = base.scroll_tree_index();
   offset_to_transform_parent_ =
       ProtoToVector2dF(base.offset_to_transform_parent());
   double_sided_ = base.double_sided();
   draws_content_ = base.draws_content();
   hide_layer_and_subtree_ = base.hide_layer_and_subtree();
   has_render_surface_ = base.has_render_surface();
   masks_to_bounds_ = base.masks_to_bounds();
   main_thread_scrolling_reasons_ = base.main_thread_scrolling_reasons();
   have_wheel_event_handlers_ = base.have_wheel_event_handlers();
   have_scroll_event_handlers_ = base.have_scroll_event_handlers();
@@ skipping 460 matching lines @@
       this, layer_tree_host_->property_trees()->transform_tree);
 }
 
 gfx::Transform Layer::screen_space_transform() const {
   DCHECK_NE(transform_tree_index_, -1);
   return ScreenSpaceTransformFromPropertyTrees(
       this, layer_tree_host_->property_trees()->transform_tree);
 }
 
 }  // namespace cc