mac: Move more 10.7 api stuff into sdk_forward_declarations.h

ui/snapshot/snapshot_mac_unittest.mm

 // 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.
 
 #include "ui/snapshot/snapshot.h"
 
 #import <Cocoa/Cocoa.h>
 
+#include "base/mac/sdk_forward_declarations.h"
 #include "base/memory/scoped_nsobject.h"
 #include "base/memory/scoped_ptr.h"
 #include "testing/platform_test.h"
 #include "ui/gfx/rect.h"
 
-#if !defined(MAC_OS_X_VERSION_10_7) || \
-    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_7
-
-@interface NSWindow (LionAPI)
-- (CGFloat)backingScaleFactor;
-@end
-
-#endif  // 10.7
-
 namespace ui {
 namespace {
 
 typedef PlatformTest GrabWindowSnapshotTest;
 
 TEST_F(GrabWindowSnapshotTest, TestGrabWindowSnapshot) {
   // Launch a test window so we can take a snapshot.
   NSRect frame = NSMakeRect(0, 0, 400, 400);
   scoped_nsobject<NSWindow> window(
       [[NSWindow alloc] initWithContentRect:frame
@@ skipping 20 matching lines @@
     scaleFactor = [window backingScaleFactor];
   EXPECT_EQ(400 * scaleFactor, CGImageGetWidth([rep CGImage]));
   NSColor* color = [rep colorAtX:200 * scaleFactor y:200 * scaleFactor];
   CGFloat red = 0, green = 0, blue = 0, alpha = 0;
   [color getRed:&red green:&green blue:&blue alpha:&alpha];
   EXPECT_GE(red + green + blue, 3.0);
 }
 
 }  // namespace
 }  // namespace ui