Fixing crash upon window manager creation

BUG=452608
TEST=existing unit tests

Review URL: https://codereview.chromium.org/890293002

Cr-Commit-Position: refs/heads/master@{#314276}

chrome/browser/chromeos/extensions/wallpaper_private_api_unittest.cc

@@ -223,6 +223,7 @@ void WallpaperPrivateApiMultiUserUnittest::SetUpMultiUserWindowManager(
     chrome::MultiUserWindowManager::MultiProfileMode mode) {
   multi_user_window_manager_ =
       new chrome::MultiUserWindowManagerChromeOS(active_user_id);
+  multi_user_window_manager_->Init();
   chrome::MultiUserWindowManager::SetInstanceForTest(
       multi_user_window_manager_, mode);
   // We do not want animations while the test is going on.

chrome/browser/notifications/message_center_notifications_unittest.cc

@@ -146,6 +146,7 @@ TEST_F(MessageCenterNotificationManagerTest, MultiUserUpdates) {
   std::string active_user_id = multi_user_util::GetUserIDFromProfile(&profile);
   chrome::MultiUserWindowManagerChromeOS* multi_user_window_manager =
       new chrome::MultiUserWindowManagerChromeOS(active_user_id);
+  multi_user_window_manager->Init();
   chrome::MultiUserWindowManager::SetInstanceForTest(
       multi_user_window_manager,
       chrome::MultiUserWindowManager::MULTI_PROFILE_MODE_SEPARATED);

chrome/browser/ui/ash/multi_user/multi_user_context_menu_chromeos_unittest.cc

@@ -60,6 +60,7 @@ void MultiUserContextMenuChromeOSTest::SetUp() {
   window_->Show();
 
   multi_user_window_manager_ = new chrome::MultiUserWindowManagerChromeOS("A");
+  multi_user_window_manager_->Init();
   chrome::MultiUserWindowManager::SetInstanceForTest(multi_user_window_manager_,
         chrome::MultiUserWindowManager::MULTI_PROFILE_MODE_SEPARATED);
   EXPECT_TRUE(multi_user_window_manager_);

chrome/browser/ui/ash/multi_user/multi_user_window_manager.cc

@@ -42,11 +42,13 @@ MultiUserWindowManager* MultiUserWindowManager::CreateInstance() {
       ash::MultiProfileUMA::SESSION_SINGLE_USER_MODE;
   if (!g_instance &&
       ash::Shell::GetInstance()->delegate()->IsMultiProfilesEnabled()) {
-    g_instance =
+    MultiUserWindowManagerChromeOS* manager =
         new MultiUserWindowManagerChromeOS(ash::Shell::GetInstance()
                                                ->session_state_delegate()
                                                ->GetUserInfo(0)
                                                ->GetUserID());
+    g_instance = manager;
+    manager->Init();
     multi_user_mode_ = MULTI_PROFILE_MODE_SEPARATED;
     mode = ash::MultiProfileUMA::SESSION_SEPARATE_DESKTOP_MODE;
   } else if (ash::Shell::GetInstance()->delegate()->IsMultiProfilesEnabled()) {

chrome/browser/ui/ash/multi_user/multi_user_window_manager_chromeos.cc

@@ -215,20 +215,6 @@ MultiUserWindowManagerChromeOS::MultiUserWindowManagerChromeOS(
           message_center::MessageCenter::Get(), current_user_id)),
       suppress_visibility_changes_(false),
       animation_speed_(ANIMATION_SPEED_NORMAL) {
-  // Add a session state observer to be able to monitor session changes.
-  if (ash::Shell::HasInstance())
-    ash::Shell::GetInstance()->session_state_delegate()->
-        AddSessionStateObserver(this);
-
-  // The BrowserListObserver would have been better to use then the old
-  // notification system, but that observer fires before the window got created.
-  registrar_.Add(this, NOTIFICATION_BROWSER_WINDOW_READY,
-                 content::NotificationService::AllSources());
-
-  // Add an app window observer & all already running apps.
-  Profile* profile = multi_user_util::GetProfileFromUserID(current_user_id);
-  if (profile)
-    AddUser(profile);
 }
 
 MultiUserWindowManagerChromeOS::~MultiUserWindowManagerChromeOS() {
@@ -264,6 +250,29 @@ MultiUserWindowManagerChromeOS::~MultiUserWindowManagerChromeOS() {
         RemoveSessionStateObserver(this);
 }
 
+void MultiUserWindowManagerChromeOS::Init() {
+  // Since we are setting the SessionStateObserver and adding the user, this
+  // function should get called only once.
+  DCHECK(user_id_to_app_observer_.find(current_user_id_) ==
+             user_id_to_app_observer_.end());
+
+  // Add a session state observer to be able to monitor session changes.
+  if (ash::Shell::HasInstance()) {
+    ash::Shell::GetInstance()->session_state_delegate()->
+        AddSessionStateObserver(this);
+  }
+
+  // The BrowserListObserver would have been better to use then the old
+  // notification system, but that observer fires before the window got created.
+  registrar_.Add(this, NOTIFICATION_BROWSER_WINDOW_READY,
+                 content::NotificationService::AllSources());
+
+  // Add an app window observer & all already running apps.
+  Profile* profile = multi_user_util::GetProfileFromUserID(current_user_id_);
+  if (profile)
+    AddUser(profile);
+}
+
 void MultiUserWindowManagerChromeOS::SetWindowOwner(
     aura::Window* window,
     const std::string& user_id) {

chrome/browser/ui/ash/multi_user/multi_user_window_manager_chromeos.h

@@ -72,6 +72,9 @@ class MultiUserWindowManagerChromeOS
   explicit MultiUserWindowManagerChromeOS(const std::string& active_user_id);
   ~MultiUserWindowManagerChromeOS() override;
 
+  // Initializes the manager after its creation. Should only be called once.
+  void Init();
+
   // MultiUserWindowManager overrides:
   void SetWindowOwner(
       aura::Window* window, const std::string& user_id) override;

chrome/browser/ui/ash/multi_user/multi_user_window_manager_chromeos_unittest.cc

@@ -180,6 +180,7 @@ void MultiUserWindowManagerChromeOSTest::SetUpForThisManyWindows(int windows) {
     window_[i]->Show();
   }
   multi_user_window_manager_ = new chrome::MultiUserWindowManagerChromeOS("A");
+  multi_user_window_manager_->Init();
   multi_user_window_manager_->SetAnimationSpeedForTest(
       chrome::MultiUserWindowManagerChromeOS::ANIMATION_SPEED_DISABLED);
   chrome::MultiUserWindowManager::SetInstanceForTest(multi_user_window_manager_,