Add a path to use CALayers to display content

base/mac/sdk_forward_declarations.h

 // Copyright (c) 2012 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.
 
 // This file contains forward declarations for items in later SDKs than the
 // default one with which Chromium is built (currently 10.6).
 
 #ifndef BASE_MAC_SDK_FORWARD_DECLARATIONS_H_
 #define BASE_MAC_SDK_FORWARD_DECLARATIONS_H_
 
@@ skipping 25 matching lines @@
           dampenAmountThresholdMin:(CGFloat)minDampenThreshold
                                max:(CGFloat)maxDampenThreshold
                       usingHandler:(void (^)(CGFloat gestureAmount,
                                              NSEventPhase phase,
                                              BOOL isComplete,
                                              BOOL *stop))trackingHandler;
 
 - (BOOL)isDirectionInvertedFromDevice;
 
 @end
+
+@interface CALayer (LionAPI)
+- (CGFloat)contentsScale;
+- (void)setContentsScale:(CGFloat)contentsScale;
+@end
+
 #endif  // MAC_OS_X_VERSION_10_7
 
 #endif  // BASE_MAC_SDK_FORWARD_DECLARATIONS_H_