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

cc/layers/layer_deserializer_unittest.cc

+// 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_deserializer.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 {
+namespace {
+
+class LayerDeserializerTest : public testing::Test {

[vmpstr, 2015/10/21 22:34:14]

Do you need this? Can you just do TEST(LayerDeserializerTest, TestKeepingRoot)
instead of TEST_F?

[nyquist, 2015/10/23 00:12:31]

Done.

+ public:
+  LayerDeserializerTest() {}
+};
+
+}  // namespace
+
+TEST_F(LayerDeserializerTest, 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;
+  child_a_node.set_id(442);

[vmpstr, 2015/10/21 22:34:14]

Same ids for a and b?

[nyquist, 2015/10/23 00:12:30]

Doh! Fixed.

+  child_a_node.set_type(proto::LayerType::Base);
+  child_a_node.set_parent_id(old_root->id());  // root_node
+
+  proto::LayerNode child_b_node;
+  child_b_node.set_id(442);
+  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_c_node.set_id(443);
+  child_c_node.set_type(proto::LayerType::Base);
+  child_c_node.set_parent_id(442);  // child_b_node
+
+  scoped_refptr<Layer> new_root =
+      LayerDeserializer::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());

[vmpstr, 2015/10/21 22:34:14]

Can you verify the full structure here?

[nyquist, 2015/10/23 00:12:30]

Done here and below. Also updated how the structure is set up a little bit. Same
structure, different code.

+}
+
+TEST_F(LayerDeserializerTest, 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;
+  child_a_node.set_id(442);
+  child_a_node.set_type(proto::LayerType::Base);
+  child_a_node.set_parent_id(441);  // root_node
+
+  proto::LayerNode child_b_node;
+  child_b_node.set_id(442);
+  child_b_node.set_type(proto::LayerType::Base);
+  child_b_node.set_parent_id(441);  // root_node
+
+  proto::LayerNode child_c_node;
+  child_c_node.set_id(443);
+  child_c_node.set_type(proto::LayerType::Base);
+  child_c_node.set_parent_id(442);  // child_b_node
+
+  scoped_refptr<Layer> old_root = Layer::Create(LayerSettings());
+  scoped_refptr<Layer> new_root =
+      LayerDeserializer::DeserializeLayerHierarchy(old_root, root_node);
+
+  // The new root should not be the same as the old root.
+  EXPECT_EQ(441, new_root->id());
+}
+
+}  // namespace cc