Consolidate SDK forwards in sdk_forward_declarations.h.

content/browser/theme_helper_mac.mm

 // 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 "content/browser/theme_helper_mac.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/command_line.h"
+#include "base/mac/sdk_forward_declarations.h"
 #include "content/common/view_messages.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_types.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/common/content_switches.h"
 
 // Declare notification names from the 10.7 SDK.
 #if !defined(MAC_OS_X_VERSION_10_7) || \
     MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_7
+
 NSString* NSPreferredScrollerStyleDidChangeNotification =
     @"NSPreferredScrollerStyleDidChangeNotification";
 
-@interface NSScroller (LionSDK)
-+ (NSInteger)preferredScrollerStyle;
-@end
 #endif
 
 @interface ScrollbarPrefsObserver : NSObject
 
 + (void)registerAsObserver;
 + (void)appearancePrefsChanged:(NSNotification*)notification;
 + (void)behaviorPrefsChanged:(NSNotification*)notification;
 + (void)notifyPrefsChangedWithRedraw:(BOOL)redraw;
 
 @end
@@ skipping 106 matching lines @@
   RenderProcessHost* rph = Source<RenderProcessHost>(source).ptr();
   rph->Send(new ViewMsg_UpdateScrollbarTheme(
       [defaults floatForKey:@"NSScrollerButtonDelay"],
       [defaults floatForKey:@"NSScrollerButtonPeriod"],
       [defaults boolForKey:@"AppleScrollerPagingBehavior"],
       GetPreferredScrollerStyle(),
       false));
 }
 
 }  // namespace content