Remove all the OS X 10.6 SDK forward declarations.

chrome/browser/mac/security_wrappers.h

Index: chrome/browser/mac/security_wrappers.h
diff --git a/chrome/browser/mac/security_wrappers.h b/chrome/browser/mac/security_wrappers.h
index 22d05db33ce5377dfcc6dc82a951adfc8aea1f9b..28cd75a9986507e7bb5ce5d3569678450dc85de4 100644
--- a/chrome/browser/mac/security_wrappers.h
+++ b/chrome/browser/mac/security_wrappers.h
@@ -6,27 +6,12 @@
 #define CHROME_BROWSER_MAC_SECURITY_WRAPPERS_H_
 
 #include <Security/Security.h>
+#include <Security/SecRequirement.h>
 
 #include "base/basictypes.h"
 #include "base/mac/scoped_cftyperef.h"
 #include "base/memory/scoped_ptr.h"
 
-#if defined(MAC_OS_X_VERSION_10_6) && \
-    MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_6
-
-#include <Security/SecRequirement.h>
-
-#else
-
-typedef struct __SecRequirement* SecRequirementRef;
-typedef uint32_t SecCSFlags;
-
-enum {
-  kSecCSDefaultFlags = 0
-};
-
-#endif
-
 namespace chrome {
 namespace browser {
 namespace mac {