Consolidate SDK forwards in sdk_forward_declarations.h.

content/common/cursors/webcursor_mac.mm

Index: content/common/cursors/webcursor_mac.mm
diff --git a/content/common/cursors/webcursor_mac.mm b/content/common/cursors/webcursor_mac.mm
index d32d8b7c9822df78cfeb0d076f62c00379f5b629..6a401321b38058ce7e7584207e4d65ca63b2950c 100644
--- a/content/common/cursors/webcursor_mac.mm
+++ b/content/common/cursors/webcursor_mac.mm
@@ -9,6 +9,7 @@
 #include "base/logging.h"
 #include "base/mac/mac_util.h"
 #include "base/mac/scoped_cftyperef.h"
+#include "base/mac/sdk_forward_declarations.h"
 #include "content/public/common/content_client.h"
 #include "grit/webkit_resources.h"
 #include "skia/ext/skia_utils_mac.h"
@@ -22,16 +23,6 @@
 using blink::WebCursorInfo;
 using blink::WebSize;
 
-// Declare symbols that are part of the 10.7 SDK.
-#if !defined(MAC_OS_X_VERSION_10_7) || \
-    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_7
-
-@interface NSCursor (LionSDKDeclarations)
-+ (NSCursor*)IBeamCursorForVerticalLayout;
-@end
-
-#endif  // MAC_OS_X_VERSION_10_7
-
 // Private interface to CoreCursor, as of Mac OS X 10.7. This is essentially the
 // implementation of WKCursor in WebKitSystemInterface.