Use OnceCallback on Mojo interfaces in //ash

ash/session/session_controller.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/session/session_controller.h"
 
 #include <algorithm>
+#include <utility>
 
 #include "ash/session/session_observer.h"
 #include "ash/shell.h"
 #include "ash/system/power/power_event_observer.h"
 #include "ash/wm/lock_state_controller.h"
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "chromeos/chromeos_switches.h"
 #include "components/signin/core/account_id/account_id.h"
@@ skipping 214 matching lines @@
   if (user_sessions_[0]->session_id != active_session_id_) {
     active_session_id_ = user_sessions_[0]->session_id;
 
     for (auto& observer : observers_)
       observer.OnActiveUserSessionChanged(user_sessions_[0]->account_id);
 
     UpdateLoginStatus();
   }
 }
 
-void SessionController::StartLock(const StartLockCallback& callback) {
+void SessionController::StartLock(StartLockCallback callback) {
   DCHECK(start_lock_callback_.is_null());
-  start_lock_callback_ = callback;
+  start_lock_callback_ = std::move(callback);
 
   LockStateController* const lock_state_controller =
       Shell::Get()->lock_state_controller();
 
   lock_state_controller->SetLockScreenDisplayedCallback(
       base::Bind(&SessionController::OnLockAnimationFinished,
                  weak_ptr_factory_.GetWeakPtr()));
   lock_state_controller->OnStartingLock();
 }
 
 void SessionController::NotifyChromeLockAnimationsComplete() {
   Shell::Get()->power_event_observer()->OnLockAnimationsComplete();
 }
 
 void SessionController::RunUnlockAnimation(
-    const RunUnlockAnimationCallback& callback) {
+    RunUnlockAnimationCallback callback) {
   is_unlocking_ = true;
 
   // Shell could have no instance in tests.
   if (Shell::HasInstance())
-    Shell::Get()->lock_state_controller()->OnLockScreenHide(callback);
+    Shell::Get()->lock_state_controller()->OnLockScreenHide(
+        std::move(callback));
 }
 
 void SessionController::NotifyChromeTerminating() {
   for (auto& observer : observers_)
     observer.OnChromeTerminating();
 }
 
 void SessionController::ClearUserSessionsForTest() {
   user_sessions_.clear();
 }
@@ skipping 104 matching lines @@
   for (auto& observer : observers_)
     observer.OnLoginStatusChanged(login_status_);
 }
 
 void SessionController::OnLockAnimationFinished() {
   if (!start_lock_callback_.is_null())
     std::move(start_lock_callback_).Run(true /* locked */);
 }
 
 }  // namespace ash