Improve spelling of "notification".

ui/message_center/cocoa/tray_view_controller.mm

 // 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.
 
 #import "ui/message_center/cocoa/tray_view_controller.h"
 
 #include <cmath>
 
 #include "base/mac/scoped_nsautorelease_pool.h"
 #include "base/time/time.h"
@@ skipping 38 matching lines @@
 // Update both tray view and window by resizing it to fit its content.
 - (void)updateTrayViewAndWindow;
 
 // Remove notifications dismissed by the user. It is done in the following
 // 3 steps.
 - (void)closeNotificationsByUser;
 
 // Step 1: hide all notifications pending removal with fade-out animation.
 - (void)hideNotificationsPendingRemoval;
 
-// Step 2: move up all remaining notfications to take over the available space
+// Step 2: move up all remaining notifications to take over the available space
 // due to hiding notifications. The scroll view and the window remain unchanged.
 - (void)moveUpRemainingNotifications;
 
 // Step 3: finalize the tray view and window to get rid of the empty space.
 - (void)finalizeTrayViewAndWindow;
 
 // Clear a notification by sliding it out from left to right. This occurs when
 // "Clear All" is clicked.
 - (void)clearOneNotification;
 
-// When all visible notificatons slide out, re-enable controls and remove
+// When all visible notifications slide out, re-enable controls and remove
 // notifications from the message center.
 - (void)finalizeClearAll;
 
 // Sets the images of the quiet mode button based on the message center state.
 - (void)updateQuietModeButtonImage;
 @end
 
 namespace {
 
 // The duration of fade-out and bounds animation.
@@ skipping 718 matching lines @@
     [pauseButton_ setDefaultImage: rb.GetNativeImageNamed(
         IDR_NOTIFICATION_DO_NOT_DISTURB_PRESSED).ToNSImage()];
   } else {
     [pauseButton_ setTrackingEnabled:YES];
     [pauseButton_ setDefaultImage:
         rb.GetNativeImageNamed(IDR_NOTIFICATION_DO_NOT_DISTURB).ToNSImage()];
   }
 }
 
 @end