Fixing crash upon window manager creation

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

 // Copyright 2013 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 "chrome/browser/ui/ash/multi_user/multi_user_window_manager_chromeos.h"
 
 #include "ash/ash_switches.h"
 #include "ash/multi_profile_uma.h"
 #include "ash/root_window_controller.h"
 #include "ash/session/session_state_delegate.h"
@@ skipping 197 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(AppObserver);
 };
 
 MultiUserWindowManagerChromeOS::MultiUserWindowManagerChromeOS(
     const std::string& current_user_id)
     : current_user_id_(current_user_id),
       notification_blocker_(new MultiUserNotificationBlockerChromeOS(
           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() {
   // When the MultiUserWindowManager gets destroyed, ash::Shell is mostly gone.
   // As such we should not try to finalize any outstanding user animations.
   // Note that the destruction of the object can be done later.
   if (animation_.get())
     animation_->CancelAnimation();
 
   // Remove all window observers.
@@ skipping 15 matching lines @@
     delete app_observer_iterator->second;
     user_id_to_app_observer_.erase(app_observer_iterator);
     app_observer_iterator = user_id_to_app_observer_.begin();
   }
 
   if (ash::Shell::HasInstance())
     ash::Shell::GetInstance()->session_state_delegate()->
         RemoveSessionStateObserver(this);
 }
 
+void MultiUserWindowManagerChromeOS::Init() {
+  // We should call this function only once.
+  DCHECK(user_id_to_app_observer_.find(current_user_id_) ==
+             user_id_to_app_observer_.end());

[stevenjb, 2015/02/03 01:31:58]

nit: This only actually ensures that we don't call AddUser more than once, which
will only be true if  multi_user_util::GetProfileFromUserID(current_user_id_)
returns a valid Profile below. We may want to test that first, or at least
clarify the comment a little.

[Mr4D (OOO till 08-26), 2015/02/03 02:06:05]

We add the observer as well - so it is not only the AddUser which gets called in
that special case. Generally speaking an Init function should not get called
several times. But I changed the comment slightly.

+
+  // Add a session state observer to be able to monitor session changes.
+  if (ash::Shell::HasInstance())
+    ash::Shell::GetInstance()->session_state_delegate()->
+        AddSessionStateObserver(this);

[stevenjb, 2015/02/03 01:31:58]

nit: {}

[Mr4D (OOO till 08-26), 2015/02/03 02:06:05]

Done.

+
+  // 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) {
   // Make sure the window is valid and there was no owner yet.
   DCHECK(window);
   DCHECK(!user_id.empty());
   if (GetWindowOwner(window) == user_id)
     return;
   DCHECK(GetWindowOwner(window).empty());
   window_to_entry_[window] = new WindowEntry(user_id);
@@ skipping 452 matching lines @@
   DCHECK_EQ(visible, window->IsVisible());
 }
 
 int MultiUserWindowManagerChromeOS::GetAdjustedAnimationTimeInMS(
     int default_time_in_ms) const {
   return animation_speed_ == ANIMATION_SPEED_NORMAL ? default_time_in_ms :
       (animation_speed_ == ANIMATION_SPEED_FAST ? 10 : 0);
 }
 
 }  // namespace chrome