Subject .mm files to the header sorting presubmit

chrome/browser/ui/cocoa/bookmarks/bookmark_bar_folder_hover_state.mm

 // Copyright (c) 2011 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 "chrome/browser/ui/cocoa/bookmarks/bookmark_bar_folder_hover_state.h"
+
 #import "chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.h"
 
 @interface BookmarkBarFolderHoverState(Private)
 - (void)setHoverState:(HoverState)state;
 - (void)closeBookmarkFolderOnHoverButton:(BookmarkButton*)button;
 - (void)openBookmarkFolderOnHoverButton:(BookmarkButton*)button;
 @end
 
 @implementation BookmarkBarFolderHoverState
 
@@ skipping 151 matching lines @@
 // Called after a delay to open a new hover folder.
 // Note: this method is not meant to be invoked directly, only through
 // a delayed call to |scheduleOpenBookmarkFolderOnHoverButton:|.
 - (void)openBookmarkFolderOnHoverButton:(BookmarkButton*)button {
   [self setHoverState:kHoverStateOpen];
   [[button target] performSelector:@selector(openBookmarkFolderFromButton:)
       withObject:button];
 }
 
 @end