Consolidate SDK forwards in sdk_forward_declarations.h.

ui/app_list/cocoa/scroll_view_with_no_scrollbars.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 "ui/app_list/cocoa/scroll_view_with_no_scrollbars.h"
 
 #include "base/mac/mac_util.h"
 #include "base/mac/scoped_cftyperef.h"
 #include "base/mac/scoped_nsobject.h"
-
-#if !defined(MAC_OS_X_VERSION_10_7) || \
-    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_7
-
-enum {
-   NSEventPhaseNone       = 0,
-   NSEventPhaseBegan      = 0x1 << 0,
-   NSEventPhaseStationary = 0x1 << 1,
-   NSEventPhaseChanged    = 0x1 << 2,
-   NSEventPhaseEnded      = 0x1 << 3,
-   NSEventPhaseCancelled  = 0x1 << 4,
-};
-typedef NSUInteger NSEventPhase;
-
-@interface NSEvent (LionAPI)
-
-- (NSEventPhase)momentumPhase;
-- (NSEventPhase)phase;
-
-@end
-
-#endif  // 10.7
+#include "base/mac/sdk_forward_declarations.h"
 
 @interface InvisibleScroller : NSScroller;
 @end
 
 @implementation InvisibleScroller
 
 // Makes it non-interactive (and invisible) on Lion with both 10.6 and 10.7
 // SDKs. TODO(tapted): Find a way to make it non-interactive on Snow Leopard.
 // TODO(tapted): Find a way to make it take up no space on Lion with a 10.6 SDK.
 - (NSRect)rectForPart:(NSScrollerPart)aPart {
@@ skipping 48 matching lines @@
     return;
 
   BOOL scrollComplete = [event momentumPhase] == NSEventPhaseEnded ||
       ([event momentumPhase] == NSEventPhaseNone &&
           [event phase] == NSEventPhaseEnded);
 
   [delegate_ userScrolling:!scrollComplete];
 }
 
 @end