ServiceWorker: Drop statechange events if WebServiceWorkerProxy is not ready

content/child/service_worker/web_service_worker_impl.cc

Index: content/child/service_worker/web_service_worker_impl.cc
diff --git a/content/child/service_worker/web_service_worker_impl.cc b/content/child/service_worker/web_service_worker_impl.cc
index f856cf82aedb3980fa9d2fd027f7c8ae629c2acd..f7e111c2f342d9aae1772e1c4aa39072b08d727d 100644
--- a/content/child/service_worker/web_service_worker_impl.cc
+++ b/content/child/service_worker/web_service_worker_impl.cc
@@ -58,7 +58,11 @@ WebServiceWorkerImpl::~WebServiceWorkerImpl() {
 void WebServiceWorkerImpl::OnStateChanged(
     blink::WebServiceWorkerState new_state) {
   state_ = new_state;
-  proxy_->dispatchStateChangeEvent();
+
+  // TODO(nhiroki): This is a quick fix for http://crbug.com/507110
+  DCHECK(proxy_);
+  if (proxy_)
+    proxy_->dispatchStateChangeEvent();
 }
 
 void WebServiceWorkerImpl::setProxy(blink::WebServiceWorkerProxy* proxy) {