RefCounted types should not have public destructors, delegate cleanup

For Delegate/Observer-type classes that specify an
interface but do not have any particular lifetime
requirements, make their destructors protected. This is to
allow their interfaces to be implemented safely by
RefCounted types. With public destructors, it's possible to
do "scoped_ptr<Delegate> foo", and then assign a
RefCountedDelegateImpl, which would lead to a double free.

As none of these Delegates actually need public destructors
(ownership of the Delegate* is not transferred during a
function call / class constructor), mark the destructors
protected so that it becomes a compile warning to try to
delete them via the Delegate*.

BUG=123295
TEST=it compiles


Review URL: https://chromiumcodereview.appspot.com/10383262

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@144086 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 3 insertions, 2 deletions

diff --git a/chrome/common/pref_store.h b/chrome/common/pref_store.h
index 67fa4c9..1b63eb2 100644
--- a/chrome/common/pref_store.h
+++ b/chrome/common/pref_store.h
@@ -27,12 +27,13 @@ class PrefStore : public base::RefCounted<PrefStore> {
   // Observer interface for monitoring PrefStore.
   class Observer {
    public:
-    virtual ~Observer() {}
-
     // Called when the value for the given |key| in the store changes.
     virtual void OnPrefValueChanged(const std::string& key) = 0;
     // Notification about the PrefStore being fully initialized.
     virtual void OnInitializationCompleted(bool succeeded) = 0;
+
+   protected:
+    virtual ~Observer() {}
   };
 
   // Return values for GetValue().