[cros] Define session_manager component with SessionManager base class

components/session_manager/core/session_manager.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 "components/session_manager/core/session_manager.h"
+
+#include "base/logging.h"
+
+namespace session_manager {
+
+SessionManager::SessionManager() : session_state_(SESSION_STATE_UNKNOWN) {
+}
+
+SessionManager::~SessionManager() {
+}
+
+void SessionManager::SetSessionState(SessionState state) {
+  VLOG(1) << "Changing session state to: " << state;
+
+  if (session_state_ != state) {
+    // TODO(nkostylev): Notify observers about the state change.
+    // TODO(nkostylev): Add code to process session state change and probably
+    // replace delegate_ if needed.
+    session_state_ = state;
+  }
+}
+
+void SessionManager::Initialize(SessionManagerDelegate* delegate) {
+  DCHECK(delegate);
+  delegate_.reset(delegate);
+  delegate_->SetSessionManager(this);
+}
+
+void SessionManager::Start() {
+  delegate_->Start();
+}
+
+SessionManagerDelegate::SessionManagerDelegate() : session_manager_(NULL) {
+}
+
+SessionManagerDelegate::~SessionManagerDelegate() {
+}
+
+void SessionManagerDelegate::SetSessionManager(
+    session_manager::SessionManager* session_manager) {
+  session_manager_ = session_manager;
+}
+
+}  // namespace session_manager