chromeos: Fix shelf appearing at login screen under mash

ash/common/wm_shell.cc

 // Copyright 2016 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 "ash/common/wm_shell.h"
 
 #include <utility>
 
 #include "ash/common/accelerators/accelerator_controller.h"
 #include "ash/common/accelerators/ash_focus_manager_factory.h"
@@ skipping 133 matching lines @@
 void WmShell::CreateShelf() {
   // Must occur after SessionStateDelegate creation and user login.
   DCHECK(GetSessionStateDelegate());
   DCHECK_GT(GetSessionStateDelegate()->NumberOfLoggedInUsers(), 0);
   CreateShelfDelegate();
 
   for (WmWindow* root_window : GetAllRootWindows())
     root_window->GetRootWindowController()->CreateShelf();
 }
 
-void WmShell::ShowShelf() {
-  for (WmWindow* root_window : GetAllRootWindows())
-    root_window->GetRootWindowController()->ShowShelf();
-}
-
 void WmShell::CreateShelfDelegate() {
   // May be called multiple times as shelves are created and destroyed.
   if (shelf_delegate_)
     return;
   // Must occur after SessionStateDelegate creation and user login because
   // Chrome's implementation of ShelfDelegate assumes it can get information
   // about multi-profile login state.
   DCHECK(GetSessionStateDelegate());
   DCHECK_GT(GetSessionStateDelegate()->NumberOfLoggedInUsers(), 0);
   shelf_delegate_.reset(delegate_->CreateShelfDelegate(shelf_model()));
@@ skipping 96 matching lines @@
       system_tray_notifier_(base::MakeUnique<SystemTrayNotifier>()),
       wallpaper_delegate_(delegate_->CreateWallpaperDelegate()),
       window_cycle_controller_(base::MakeUnique<WindowCycleController>()),
       window_selector_controller_(
           base::MakeUnique<WindowSelectorController>()) {
 #if defined(OS_CHROMEOS)
   brightness_control_delegate_.reset(new system::BrightnessControllerChromeos);
   keyboard_brightness_control_delegate_.reset(new KeyboardBrightnessController);
   vpn_list_ = base::MakeUnique<VpnList>();
 #endif
+  session_controller_->AddSessionStateObserver(this);
 }
 
-WmShell::~WmShell() {}
+WmShell::~WmShell() {
+  session_controller_->RemoveSessionStateObserver(this);
+}
 
 WmRootWindowController* WmShell::GetPrimaryRootWindowController() {
   return GetPrimaryRootWindow()->GetRootWindowController();
 }
 
 WmWindow* WmShell::GetRootWindowForNewWindows() {
   if (scoped_root_window_for_new_windows_)
     return scoped_root_window_for_new_windows_;
   return root_window_for_new_windows_;
 }
@@ skipping 120 matching lines @@
 
 void WmShell::DeleteToastManager() {
   toast_manager_.reset();
 }
 
 void WmShell::SetAcceleratorController(
     std::unique_ptr<AcceleratorController> accelerator_controller) {
   accelerator_controller_ = std::move(accelerator_controller);
 }
 
+void WmShell::SessionStateChanged(session_manager::SessionState state) {
+  // Create the shelf when the first session becomes active. There's no need to
+  // recreate it when multiprofile sessions are added.
+  if (state != session_manager::SessionState::ACTIVE || first_session_active_)
+    return;
+
+  WmShell::Get()->CreateShelf();

[msw, 2016/12/20 15:37:30]

Isn't WmShell::Get() equivalent to |this|, and not needed?

[James Cook, 2016/12/20 17:27:19]

Whoops, done.

+  first_session_active_ = true;

[msw, 2016/12/20 15:37:30]

Should this ever be reset to false, eg. when the user logs out, or is the
WmShell object destroyed then? Otherwise, it seems like the second user to log
in won't get a shelf, right? You can go back to calling CreateShelf multiple
times if that's safe (with a comment to that effect).

[James Cook, 2016/12/20 17:27:19]

Changed to always attempt to create the shelf (which is safe) and added a
comment. I'm pretty sure that logout restarts the browser, but there's no harm
in calling it twice. This will also make it easier to switch to "PopulateShelf"
in the future when we always create the ShelfView.

+}
+
 }  // namespace ash