Don't post tasks from RulesRegistry c-tor

chrome/browser/extensions/api/web_request/web_request_api.cc

Index: chrome/browser/extensions/api/web_request/web_request_api.cc
diff --git a/chrome/browser/extensions/api/web_request/web_request_api.cc b/chrome/browser/extensions/api/web_request/web_request_api.cc
index e104f92590533804ab6a5b10e6f0526ceeb03810..db42081cb049c07c027dc527bf0fa5167e2e993c 100644
--- a/chrome/browser/extensions/api/web_request/web_request_api.cc
+++ b/chrome/browser/extensions/api/web_request/web_request_api.cc
@@ -1961,10 +1961,11 @@ bool ExtensionWebRequestEventRouter::ProcessDeclarativeRules(
   for (RelevantRegistries::iterator i = relevant_registries.begin();
        i != relevant_registries.end(); ++i) {
     extensions::WebRequestRulesRegistry* rules_registry = i->first;
-    if (!rules_registry->ready().is_signaled()) {
+    const extensions::OneShotEvent* ready = rules_registry->ready();
+    if (ready && !ready->is_signaled()) {
       // The rules registry is still loading. Block this request until it
       // finishes.
-      rules_registry->ready().Post(
+      ready->Post(
           FROM_HERE,
           base::Bind(&ExtensionWebRequestEventRouter::OnRulesRegistryReady,
                      AsWeakPtr(),