mozart: Initial commit of the view manager.

services/ui/view_manager/view_tree_state.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 "base/logging.h"
+#include "services/ui/view_manager/view_tree_state.h"
+
+namespace view_manager {
+
+ViewTreeState::ViewTreeState(mojo::ui::ViewTreePtr view_tree)
+    : root_was_set(false),
+      layout_request_pending(false),
+      layout_request_issued(false),
+      view_tree_(view_tree.Pass()),
+      root_(nullptr) {
+  DCHECK(view_tree_);
+}
+
+ViewTreeState::~ViewTreeState() {}
+
+void ViewTreeState::SetRoot(ViewState* root, uint32_t key) {
+  DCHECK(root);
+  if (root_ != root) {
+    ResetRoot();
+    root->SetTree(this, key);
+    root_ = root;
+  }
+}
+
+void ViewTreeState::ResetRoot() {
+  if (root_) {
+    root_->ResetContainer();
+  }
+  root_ = nullptr;
+}
+
+}  // namespace view_manager