Minimized windows should not be activated by another user in multiprofile scenario.

chrome/browser/ui/ash/session_state_delegate_chromeos.cc

 // Copyright (c) 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/session_state_delegate_chromeos.h"
 
 #include "ash/multi_profile_uma.h"
 #include "ash/session/session_state_observer.h"
 #include "ash/system/chromeos/multi_user/user_switch_util.h"
 #include "base/bind.h"
@@ skipping 48 matching lines @@
   return chromeos::ProfileHelper::Get()->GetProfileByUserUnsafe(user);
 }
 
 content::BrowserContext*
 SessionStateDelegateChromeos::GetBrowserContextForWindow(
     aura::Window* window) {
   const std::string& user_id =
       chrome::MultiUserWindowManager::GetInstance()->GetWindowOwner(window);
   const user_manager::User* user =
       user_manager::UserManager::Get()->FindUser(user_id);
-  DCHECK(user);
-  return chromeos::ProfileHelper::Get()->GetProfileByUserUnsafe(user);

[oshima, 2015/04/07 19:53:44]

why this change?

[xdai1, 2015/04/09 17:22:40]

In Login screen, we might fail this check since there is no active user at that
moment.

[oshima, 2015/04/09 17:50:48]

Why this wasn't an issue before? Do you think this is because of
crbug.com/475318?

[xdai1, 2015/04/09 22:45:25]

Because in this fix we will call this GetBrowserContextForWindow() function in
AshFocusRules::IsWindowConsideredVisibleForActivation() function, which will be
used to check if the window can be activatable even in the login screen. But
without this fix, we don't need to worry about this since we always call
GetBrowserContextForWindow() after we have an active user.

It has nothing to do with crbug.com/475318. 

[oshima, 2015/04/10 20:39:48]

what kind of "user_id" would you get if it's in login screen?

+  return user ? (chromeos::ProfileHelper::Get()->GetProfileByUserUnsafe(user))
+              : NULL;
+}
+
+const std::string& SessionStateDelegateChromeos::GetUserPresentingWindow(
+    aura::Window* window) {
+  return chrome::MultiUserWindowManager::GetInstance()->GetUserPresentingWindow(
+      window);
 }
 
 int SessionStateDelegateChromeos::GetMaximumNumberOfLoggedInUsers() const {
   // We limit list of logged in users to 10 due to memory constraints.
   // Note that 10 seems excessive, but we want to test how many users are
   // actually added to a session.
   // TODO(nkostylev): Adjust this limitation based on device capabilites.
   // http://crbug.com/230865
   return 10;
 }
@@ skipping 203 matching lines @@
 }
 
 void DoSwitchUser(const std::string& user_id) {
   user_manager::UserManager::Get()->SwitchActiveUser(user_id);
 }
 
 void SessionStateDelegateChromeos::TryToSwitchUser(
     const std::string& user_id) {
   ash::TrySwitchingActiveUser(base::Bind(&DoSwitchUser, user_id));
 }