cc: Directly use property trees to calculate clip rect

cc/trees/property_tree_builder.cc

 // Copyright 2014 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/property_tree_builder.h"
 
 #include <stddef.h>
 
 #include <map>
 #include <set>
 
 #include "cc/base/math_util.h"
 #include "cc/layers/layer.h"
 #include "cc/layers/layer_impl.h"
 #include "cc/trees/draw_property_utils.h"
 #include "cc/trees/layer_tree_host.h"
 #include "cc/trees/layer_tree_impl.h"
 #include "ui/gfx/geometry/point_f.h"
 #include "ui/gfx/geometry/vector2d_conversions.h"
 
 namespace cc {
 
 class LayerTreeHost;
 
 namespace {
 
 static const int kInvalidPropertyTreeNodeId = -1;
 static const int kRootPropertyTreeNodeId = 0;
+static const int kViewportClipTreeNodeId = 1;
 
 template <typename LayerType>
 struct DataForRecursion {
   TransformTree* transform_tree;
   ClipTree* clip_tree;
   EffectTree* effect_tree;
   ScrollTree* scroll_tree;
   LayerType* transform_tree_parent;
   LayerType* transform_fixed_parent;
   int render_target;
@@ skipping 578 matching lines @@
   if (!is_root) {
     // The effect node's transform id is used only when we create a render
     // surface. So, we can leave the default value when we don't create a render
     // surface.
     if (should_create_render_surface) {
       // In this case, we will create a transform node, so it's safe to use the
       // next available id from the transform tree as this effect node's
       // transform id.
       node.data.transform_id =
           data_from_ancestor.transform_tree->next_available_id();
+      node.data.has_unclipped_descendants =
+          (layer->num_unclipped_descendants() != 0);
     }
     node.data.clip_id = data_from_ancestor.clip_tree_parent;
   } else {
     // Root render surface acts the unbounded and untransformed to draw content
     // into. Transform node created from root layer (includes device scale
     // factor) and clip node created from root layer (include viewports) applies
     // to root render surface's content, but not root render surface itself.
     node.data.transform_id = kRootPropertyTreeNodeId;
-    node.data.clip_id = kRootPropertyTreeNodeId;
+    node.data.clip_id = kViewportClipTreeNodeId;
   }
   data_for_children->effect_tree_parent =
       data_for_children->effect_tree->Insert(node, parent_id);
   layer->SetEffectTreeIndex(data_for_children->effect_tree_parent);
   if (should_create_render_surface) {
     data_for_children->compound_transform_since_render_target =
         gfx::Transform();
     data_for_children->axis_align_since_render_target = true;
   }
   return should_create_render_surface;
@@ skipping 350 matching lines @@
   if (SkColorGetA(color) != 255)
     color = SkColorSetA(color, 255);
   BuildPropertyTreesTopLevelInternal(
       root_layer, page_scale_layer, inner_viewport_scroll_layer,
       outer_viewport_scroll_layer, overscroll_elasticity_layer,
       elastic_overscroll, page_scale_factor, device_scale_factor, viewport,
       device_transform, property_trees, color);
 }
 
 }  // namespace cc