[Mac] Added (disabled) UI for extensions sync on OS X.

chrome/browser/cocoa/sync_customize_controller.h

Index: chrome/browser/cocoa/sync_customize_controller.h
diff --git a/chrome/browser/cocoa/sync_customize_controller.h b/chrome/browser/cocoa/sync_customize_controller.h
index 32f626ebf3bb13bbda4d71ccf3ecf5618858bf45..da222039c451b8eee6ce95ba6ac0e3908ed77537 100644
--- a/chrome/browser/cocoa/sync_customize_controller.h
+++ b/chrome/browser/cocoa/sync_customize_controller.h
@@ -28,6 +28,7 @@ class ProfileSyncService;
   BOOL preferencesRegistered_;
   BOOL autofillRegistered_;
   BOOL themesRegistered_;
+  BOOL extensionsRegistered_;
 
   // The preferred flags indicate which model types the user would
   // like to sync.
@@ -35,6 +36,7 @@ class ProfileSyncService;
   BOOL preferencesPreferred_;
   BOOL autofillPreferred_;
   BOOL themesPreferred_;
+  BOOL extensionsPreferred_;
 }
 
 // syncService cannot be NULL.
@@ -54,11 +56,13 @@ class ProfileSyncService;
 @property(assign) BOOL preferencesRegistered;
 @property(assign) BOOL autofillRegistered;
 @property(assign) BOOL themesRegistered;
+@property(assign) BOOL extensionsRegistered;
 
 @property(assign) BOOL bookmarksPreferred;
 @property(assign) BOOL preferencesPreferred;
 @property(assign) BOOL autofillPreferred;
 @property(assign) BOOL themesPreferred;
+@property(assign) BOOL extensionsPreferred;
 
 @property(readonly) BOOL okEnabled;