Add a virtual destructor to WebCredentialManagerClient.

third_party/WebKit/public/platform/WebCredentialManagerClient.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef WebCredentialManagerClient_h
 #define WebCredentialManagerClient_h
 
 #include "public/platform/WebCallbacks.h"
 #include "public/platform/WebCredentialManagerError.h"
 #include "public/platform/WebVector.h"
@@ skipping 18 matching lines @@
   // Ownership of the callback is transferred to the callee for each of
   // the following methods.
   virtual void DispatchFailedSignIn(const WebCredential&,
                                     NotificationCallbacks*) {}
   virtual void DispatchStore(const WebCredential&, NotificationCallbacks*) {}
   virtual void DispatchRequireUserMediation(NotificationCallbacks*) {}
   virtual void DispatchGet(bool zero_click_only,
                            bool include_passwords,
                            const WebVector<WebURL>& federations,
                            RequestCallbacks*) {}
+
+ protected:
+  virtual ~WebCredentialManagerClient() {}
 };
 
 }  // namespace blink
 
 #endif  // WebCredentialManager_h