Switching to the correct desktop when a system modal dialog gets shown

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

Index: chrome/browser/ui/ash/multi_user/multi_user_window_manager_chromeos.cc
diff --git a/chrome/browser/ui/ash/multi_user/multi_user_window_manager_chromeos.cc b/chrome/browser/ui/ash/multi_user/multi_user_window_manager_chromeos.cc
index 2b8890cfb3e4d949d9f530fdcb5560fa28987660..cc9a66bc87e39ed0759ebaa818795c0a87774e58 100644
--- a/chrome/browser/ui/ash/multi_user/multi_user_window_manager_chromeos.cc
+++ b/chrome/browser/ui/ash/multi_user/multi_user_window_manager_chromeos.cc
@@ -8,9 +8,11 @@
 #include "apps/shell_window_registry.h"
 #include "ash/ash_switches.h"
 #include "ash/multi_profile_uma.h"
+#include "ash/root_window_controller.h"
 #include "ash/session_state_delegate.h"
 #include "ash/shell.h"
 #include "ash/shell_delegate.h"
+#include "ash/shell_window_ids.h"
 #include "ash/wm/mru_window_tracker.h"
 #include "ash/wm/window_positioner.h"
 #include "ash/wm/window_state.h"
@@ -467,6 +469,31 @@ void MultiUserWindowManagerChromeOS::SetWindowVisibility(
   if (window->IsVisible() == visible)
     return;
 
+  // Hiding a system modal dialog should not be allowed. Instead we switch to
+  // the user which is showing the system modal window.
+  if (!visible) {
+    // Get the system modal container for the window's root window.
+    ash::internal::RootWindowController* controller =

[sky, 2013/11/16 00:34:55]

Classes in internal namespaces shouldn't be used outside of the directory. So,
either RWC shouldn't be in internal or you shouldn't be using RWC. You should be
able to use GetChildById on the root.

[Mr4D (OOO till 08-26), 2013/11/16 00:54:27]

Done.

+        ash::internal::GetRootWindowController(window->GetRootWindow());
+    aura::Window* system_modal_container =
+        controller->GetContainer(
+            ash::internal::kShellWindowId_SystemModalContainer);
+    if (window->parent() == system_modal_container) {
+      // The window is system modal and we need to find the parent which owns
+      // it so that we can switch to the desktop accordingly.
+      std::string user_id = GetUserPresentingWindow(window);
+      if (user_id.empty()) {
+        aura::Window* owning_window = GetOwningWindowInTransientChain(window);
+        if (owning_window)

[sky, 2013/11/16 00:34:55]

Should this be a DCHECK? Otherwise you know 490 is going to hit?

I don't know your code enough to say if DCHECK is right here or not. Its very
likely that a system model dialog has no owner.

[Mr4D (OOO till 08-26), 2013/11/16 00:54:27]

Done.

+          user_id = GetUserPresentingWindow(owning_window);
+      }
+      DCHECK(!user_id.empty());
+      ash::Shell::GetInstance()->session_state_delegate()->SwitchActiveUser(
+          user_id);
+      return;
+    }
+  }
+
   // To avoid that these commands are recorded as any other commands, we are
   // suppressing any window entry changes while this is going on.
   base::AutoReset<bool> suppressor(&suppress_visibility_changes_, true);