[Mac] Respect natural/inverted scroll direction on Lion when gesturing.

chrome/browser/ui/cocoa/browser_window_controller_private.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_COCOA_BROWSER_WINDOW_CONTROLLER_PRIVATE_H_
 #define CHROME_BROWSER_UI_COCOA_BROWSER_WINDOW_CONTROLLER_PRIVATE_H_
 #pragma once
 
 #import "chrome/browser/ui/cocoa/browser_window_controller.h"
 
@@ skipping 105 matching lines @@
 // For versions of Mac OS that provide an "enter fullscreen" button, make one
 // appear (in a rather hacky manner). http://crbug.com/74065 : When switching
 // the fullscreen implementation to the new API, revisit how much of this
 // hacky code is necessary.
 - (void)setUpOSFullScreenButton;
 
 // On Lion, Apple introduced a new gesture for navigating pages using two-finger
 // gestures. Returns YES if two-finger gestures should be recognized.
 - (BOOL)recognizeTwoFingerGestures;
 
+// On Lion, returns YES if the scroll direction is "natural"/inverted. All other
+// OSes will return NO.
+- (BOOL)isScrollDirectionInverted;
+
 @end  // @interface BrowserWindowController(Private)
 
 
 #endif  // CHROME_BROWSER_UI_COCOA_BROWSER_WINDOW_CONTROLLER_PRIVATE_H_