WebPushClient requires a virtual destructor.

BUG=None

Review URL: https://codereview.chromium.org/338523004

git-svn-id: svn://svn.chromium.org/blink/trunk@176124 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/public/platform/WebPushClient.h

@@ -17,6 +17,7 @@ typedef WebCallbacks<WebPushRegistration, WebPushError> WebPushRegistrationCallb
 
 class WebPushClient {
 public:
+    virtual ~WebPushClient() { }
     virtual void registerPushMessaging(const WebString& senderId, WebPushRegistrationCallbacks*) = 0;
 };