cc: Remove LayerImpl::children() calls after tree synchronization

cc/layers/layer_position_constraint_unittest.cc

 // Copyright 2013 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_position_constraint.h"
 
 #include <vector>
 
 #include "cc/layers/layer.h"
 #include "cc/layers/layer_impl.h"
@@ skipping 137 matching lines @@
     LayerTreeHostCommon::CalculateDrawPropertiesForTesting(&inputs);
 
     // Since scroll deltas aren't sent back to the main thread in this test
     // setup, clear them to maintain consistent state.
     if (root_impl_) {
       SetScrollOffsetDelta(scroll_layer_impl_, gfx::Vector2dF());
       SetScrollOffsetDelta(child_impl_, gfx::Vector2dF());
       SetScrollOffsetDelta(grand_child_impl_, gfx::Vector2dF());
     }
     root_impl_ = layer_tree_host_->CommitAndCreateLayerImplTree();
-    inner_viewport_container_layer_impl_ = root_impl_->children()[0];
-    scroll_layer_impl_ = inner_viewport_container_layer_impl_->children()[0];
-    outer_viewport_container_layer_impl_ = scroll_layer_impl_->children()[0];
+    layer_tree_impl_ = root_impl_->layer_tree_impl();
+    inner_viewport_container_layer_impl_ =
+        layer_tree_impl_->LayerById(inner_viewport_container_layer_->id());
+    scroll_layer_impl_ = layer_tree_impl_->LayerById(scroll_layer_->id());
+    outer_viewport_container_layer_impl_ =
+        layer_tree_impl_->LayerById(outer_viewport_container_layer_->id());
     child_transform_layer_impl_ =
-        outer_viewport_container_layer_impl_->children()[0];
-    child_impl_ = child_transform_layer_impl_->children()[0];
-    grand_child_impl_ = child_impl_->children()[0];
-    great_grand_child_impl_ = grand_child_impl_->children()[0];
+        layer_tree_impl_->LayerById(child_transform_layer_->id());
+    child_impl_ = layer_tree_impl_->LayerById(child_->id());
+    grand_child_impl_ = layer_tree_impl_->LayerById(grand_child_->id());
+    great_grand_child_impl_ =
+        layer_tree_impl_->LayerById(great_grand_child_->id());
   }
 
  protected:
   FakeLayerTreeHostClient fake_client_;
   TestTaskGraphRunner task_graph_runner_;
   std::unique_ptr<FakeLayerTreeHost> layer_tree_host_;
   scoped_refptr<Layer> root_;
   scoped_refptr<Layer> inner_viewport_container_layer_;
   scoped_refptr<Layer> scroll_layer_;
   scoped_refptr<Layer> outer_viewport_container_layer_;
   scoped_refptr<Layer> child_transform_layer_;
   scoped_refptr<Layer> child_;
   scoped_refptr<Layer> grand_child_;
   scoped_refptr<Layer> great_grand_child_;
+  LayerTreeImpl* layer_tree_impl_;
   LayerImpl* root_impl_;
   LayerImpl* inner_viewport_container_layer_impl_;
   LayerImpl* scroll_layer_impl_;
   LayerImpl* outer_viewport_container_layer_impl_;
   LayerImpl* child_transform_layer_impl_;
   LayerImpl* child_impl_;
   LayerImpl* grand_child_impl_;
   LayerImpl* great_grand_child_impl_;
 
   LayerPositionConstraint fixed_to_top_left_;
@@ skipping 378 matching lines @@
   // to verify that we have correct order-of-operations in the final scroll
   // compensation.  Note that rotating about the center of the layer ensures we
   // do not accidentally clip away layers that we want to test.
   gfx::Transform rotation_about_z;
   rotation_about_z.Translate(50.0, 50.0);
   rotation_about_z.RotateAboutZAxis(90.0);
   rotation_about_z.Translate(-50.0, -50.0);
   fixed_position_child->SetTransform(rotation_about_z);
 
   CommitAndUpdateImplPointers();
-  LayerImpl* fixed_position_child_impl = great_grand_child_impl_->children()[0];
+  LayerImpl* fixed_position_child_impl =
+      layer_tree_impl_->LayerById(fixed_position_child->id());
 
   // Case 1: scroll delta of 0, 0
   SetScrollOffsetDelta(child_impl_, gfx::Vector2d(0, 0));
   child_impl_->SetDrawsContent(true);
   ExecuteCalculateDrawProperties(root_impl_);
 
   gfx::Transform expected_child_transform;
 
   gfx::Transform expected_grand_child_surface_draw_transform;
   expected_grand_child_surface_draw_transform.Translate(8.0, 6.0);
@@ skipping 75 matching lines @@
   EXPECT_TRANSFORMATION_MATRIX_EQ(expected_grand_child_transform,
                                   grand_child_impl_->DrawTransform());
   EXPECT_TRANSFORMATION_MATRIX_EQ(expected_great_grand_child_transform,
                                   great_grand_child_impl_->DrawTransform());
   EXPECT_TRANSFORMATION_MATRIX_EQ(expected_fixed_position_child_transform,
                                   fixed_position_child_impl->DrawTransform());
 
   // Case 4: Bottom-right fixed-position layer.
   fixed_position_child->SetPositionConstraint(fixed_to_bottom_right_);
   CommitAndUpdateImplPointers();
-  fixed_position_child_impl = great_grand_child_impl_->children()[0];
+  fixed_position_child_impl =
+      layer_tree_impl_->LayerById(fixed_position_child->id());
   SetScrollOffsetDelta(child_impl_, gfx::Vector2d(10, 30));
   SetFixedContainerSizeDelta(child_impl_, gfx::Vector2d(20, 20));
   ExecuteCalculateDrawProperties(root_impl_);
 
   // Bottom-right fixed-position layer moves as container resizes.
   expected_fixed_position_child_transform.MakeIdentity();
   // explicit canceling out the scroll delta that gets embedded in the fixed
   // position layer's surface.
   expected_fixed_position_child_transform.Translate(10.0, 30.0);
   // Also apply size delta in the child(container) layer space.
@@ skipping 40 matching lines @@
   // compensation.  Note that rotating about the center of the layer ensures we
   // do not accidentally clip away layers that we want to test.
   gfx::Transform rotation_about_z;
   rotation_about_z.Translate(50.0, 50.0);
   rotation_about_z.RotateAboutZAxis(30.0);
   rotation_about_z.Translate(-50.0, -50.0);
   child_transform_layer_->SetTransform(rotation_about_z);
   fixed_position_child->SetTransform(rotation_about_z);
 
   CommitAndUpdateImplPointers();
-  LayerImpl* fixed_position_child_impl = great_grand_child_impl_->children()[0];
+  LayerImpl* fixed_position_child_impl =
+      layer_tree_impl_->LayerById(fixed_position_child->id());
 
   // Case 1: scroll delta of 0, 0
   SetScrollOffsetDelta(child_impl_, gfx::Vector2d(0, 0));
   child_impl_->SetDrawsContent(true);
   ExecuteCalculateDrawProperties(root_impl_);
 
   gfx::Transform expected_child_transform;
   expected_child_transform.PreconcatTransform(rotation_about_z);
 
   gfx::Transform expected_grand_child_surface_draw_transform;
@@ skipping 298 matching lines @@
   grand_child_->SetPositionConstraint(fixed_to_top_left_);
   great_grand_child_->SetIsContainerForFixedPositionLayers(true);
   great_grand_child_->SetScrollClipLayerId(root_->id());
   great_great_grand_child->SetPositionConstraint(fixed_to_top_left_);
 
   CommitAndUpdateImplPointers();
 
   LayerImpl* container1 = child_impl_;
   LayerImpl* fixed_to_container1 = grand_child_impl_;
   LayerImpl* container2 = great_grand_child_impl_;
-  LayerImpl* fixed_to_container2 = container2->children()[0];
+  LayerImpl* fixed_to_container2 =
+      layer_tree_impl_->LayerById(great_great_grand_child->id());
 
   SetScrollOffsetDelta(container1, gfx::Vector2d(0, 15));
   container1->SetDrawsContent(true);
   SetScrollOffsetDelta(container2, gfx::Vector2d(30, 0));
   container2->SetDrawsContent(true);
   ExecuteCalculateDrawProperties(root_impl_);
 
   gfx::Transform expected_container1_transform;
   expected_container1_transform.Translate(0.0, -15.0);
 
@@ skipping 93 matching lines @@
   VerifySerializeAndDeserializeProto(true, false, true);
   VerifySerializeAndDeserializeProto(true, false, false);
   VerifySerializeAndDeserializeProto(false, true, true);
   VerifySerializeAndDeserializeProto(false, true, false);
   VerifySerializeAndDeserializeProto(false, false, true);
   VerifySerializeAndDeserializeProto(false, false, false);
 }
 
 }  // namespace
 }  // namespace cc