Add support for (de)serializing cc::Layer hierarchy.

cc/layers/layer_proto_converter_unittest.cc

Index: cc/layers/layer_proto_converter_unittest.cc
diff --git a/cc/layers/layer_proto_converter_unittest.cc b/cc/layers/layer_proto_converter_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..040be9760abd8c27686266e661fd463af5ed133a
--- /dev/null
+++ b/cc/layers/layer_proto_converter_unittest.cc
@@ -0,0 +1,110 @@
+// Copyright 2015 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_proto_converter.h"
+
+#include "cc/layers/layer.h"
+#include "cc/proto/layer.pb.h"
+#include "cc/trees/layer_tree_settings.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace cc {
+
+TEST(LayerProtoConverterTest, TestKeepingRoot) {
+  /* Test deserialization of a tree that looks like:
+         root
+        /   \
+       a     b
+              \
+               c
+     The old root node will be reused during deserialization.
+  */
+  scoped_refptr<Layer> old_root = Layer::Create(LayerSettings());
+  proto::LayerNode root_node;
+  root_node.set_id(old_root->id());
+  root_node.set_type(proto::LayerType::Base);
+
+  proto::LayerNode* child_a_node = root_node.add_children();
+  child_a_node->set_id(442);
+  child_a_node->set_type(proto::LayerType::Base);
+  child_a_node->set_parent_id(old_root->id());  // root_node
+
+  proto::LayerNode* child_b_node = root_node.add_children();
+  child_b_node->set_id(443);
+  child_b_node->set_type(proto::LayerType::Base);
+  child_b_node->set_parent_id(old_root->id());  // root_node
+
+  proto::LayerNode* child_c_node = child_b_node->add_children();
+  child_c_node->set_id(444);
+  child_c_node->set_type(proto::LayerType::Base);
+  child_c_node->set_parent_id(child_b_node->id());
+
+  scoped_refptr<Layer> new_root =
+      LayerProtoConverter::DeserializeLayerHierarchy(old_root, root_node);
+
+  // The new root should not be the same as the old root.
+  EXPECT_EQ(old_root->id(), new_root->id());
+  ASSERT_EQ(2u, new_root->children().size());
+  scoped_refptr<Layer> child_a = new_root->children()[0];
+  scoped_refptr<Layer> child_b = new_root->children()[1];
+
+  EXPECT_EQ(child_a_node->id(), child_a->id());
+  EXPECT_EQ(child_b_node->id(), child_b->id());
+
+  EXPECT_EQ(0u, child_a->children().size());
+  ASSERT_EQ(1u, child_b->children().size());
+
+  scoped_refptr<Layer> child_c = child_b->children()[0];
+  EXPECT_EQ(child_c_node->id(), child_c->id());
+}
+
+TEST(LayerProtoConverterTest, TestSwappingRoot) {
+  /* Test deserialization of a tree that looks like:
+         root
+        /   \
+       a     b
+              \
+               c
+     The old root node will be swapped out during deserialization.
+  */
+  proto::LayerNode root_node;
+  root_node.set_id(441);
+  root_node.set_type(proto::LayerType::Base);
+
+  proto::LayerNode* child_a_node = root_node.add_children();
+  child_a_node->set_id(442);
+  child_a_node->set_type(proto::LayerType::Base);
+  child_a_node->set_parent_id(root_node.id());
+
+  proto::LayerNode* child_b_node = root_node.add_children();
+  child_b_node->set_id(443);
+  child_b_node->set_type(proto::LayerType::Base);
+  child_b_node->set_parent_id(root_node.id());
+
+  proto::LayerNode* child_c_node = child_b_node->add_children();
+  child_c_node->set_id(444);
+  child_c_node->set_type(proto::LayerType::Base);
+  child_c_node->set_parent_id(child_b_node->id());
+
+  scoped_refptr<Layer> old_root = Layer::Create(LayerSettings());
+  scoped_refptr<Layer> new_root =
+      LayerProtoConverter::DeserializeLayerHierarchy(old_root, root_node);
+
+  // The new root should not be the same as the old root.
+  EXPECT_EQ(root_node.id(), new_root->id());
+  ASSERT_EQ(2u, new_root->children().size());
+  scoped_refptr<Layer> child_a = new_root->children()[0];
+  scoped_refptr<Layer> child_b = new_root->children()[1];
+
+  EXPECT_EQ(child_a_node->id(), child_a->id());
+  EXPECT_EQ(child_b_node->id(), child_b->id());
+
+  EXPECT_EQ(0u, child_a->children().size());
+  ASSERT_EQ(1u, child_b->children().size());
+
+  scoped_refptr<Layer> child_c = child_b->children()[0];
+  EXPECT_EQ(child_c_node->id(), child_c->id());
+}
+
+}  // namespace cc