Fix the typo "visibility".

ash/wm/lock_state_controller_unittest.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 "ash/wm/lock_state_controller.h"
 
 #include "ash/session/session_state_delegate.h"
 #include "ash/shell.h"
 #include "ash/test/ash_test_base.h"
 #include "ash/test/test_lock_state_controller_delegate.h"
@@ skipping 942 matching lines @@
   AdvancePartially(SessionStateAnimator::ANIMATION_SPEED_UNDOABLE, 0.5f);
 
   // Release the button before the lock timer fires.
   ReleasePowerButton();
   ExpectPreLockAnimationCancel();
   ExpectBackgroundIsHiding();
 
   Advance(SessionStateAnimator::ANIMATION_SPEED_UNDO_MOVE_WINDOWS);
 
   // When the CancelPrelockAnimation sequence finishes it queues up a
-  // restore background visibilty sequence when the background is hidden.
+  // restore background visibility sequence when the background is hidden.
   ExpectRestoringBackgroundVisibility();
 
   Advance(SessionStateAnimator::ANIMATION_SPEED_IMMEDIATE);
 
   ExpectUnlockedState();
 }
 
 // Test that hidden background appears and revers correctly on lock/unlock.
 TEST_F(LockStateControllerTest, TestHiddenBackgroundLockUnlock) {
   Initialize(false, user::LOGGED_IN_USER);
@@ skipping 29 matching lines @@
   ExpectUnlockBeforeUIDestroyedAnimationFinished();
 
   SystemUnlocks();
 
   ExpectUnlockAfterUIDestroyedAnimationStarted();
   ExpectBackgroundIsHiding();
 
   Advance(SessionStateAnimator::ANIMATION_SPEED_MOVE_WINDOWS);
 
   // When the StartUnlockAnimationAfterUIDestroyed sequence finishes it queues
-  // up a restore background visibilty sequence when the background is hidden.
+  // up a restore background visibility sequence when the background is hidden.
   ExpectRestoringBackgroundVisibility();
 
   Advance(SessionStateAnimator::ANIMATION_SPEED_IMMEDIATE);
 
   ExpectUnlockAfterUIDestroyedAnimationFinished();
 
   ExpectUnlockedState();
 }
 
 TEST_F(LockStateControllerTest, Screenshot) {
@@ skipping 76 matching lines @@
   ReleasePowerButton();
 
   ExpectPreLockAnimationStarted();
 
   test_animator_->CompleteAllAnimations(true);
   EXPECT_EQ(1, lock_state_controller_delegate_->num_lock_requests());
 }
 
 }  // namespace test
 }  // namespace ash