Remove knowledge of Chrome-specific SyncableService classes from WebDataService.

base/supports_user_data.h

Index: base/supports_user_data.h
diff --git a/base/supports_user_data.h b/base/supports_user_data.h
index 77367553daf5b405d5fffa138614d6a64b0234f0..b2e339b484aa3cd677bfe17dc786f207af76c6c0 100644
--- a/base/supports_user_data.h
+++ b/base/supports_user_data.h
@@ -19,6 +19,7 @@ namespace base {
 class BASE_EXPORT SupportsUserData {
  public:
   SupportsUserData();
+  virtual ~SupportsUserData();
 
   // Derive from this class and add your own data members to associate extra
   // information with this object. Alternatively, add this as a public base
@@ -42,9 +43,6 @@ class BASE_EXPORT SupportsUserData {
   // full control of the synchronization of that hand over.
   void DetachUserDataThread();
 
- protected:
-  virtual ~SupportsUserData();
-
  private:
   typedef std::map<const void*, linked_ptr<Data> > DataMap;