Restore KeyedServiceFactory diagnostics for context use-after-destroy.

chrome/browser/extensions/extension_gcm_app_handler.cc

Index: chrome/browser/extensions/extension_gcm_app_handler.cc
diff --git a/chrome/browser/extensions/extension_gcm_app_handler.cc b/chrome/browser/extensions/extension_gcm_app_handler.cc
index c1dd9a207b87e3921dd62e95246fe3707f3783db..417f8ee2bb865094711d3a1f280999501cf06349 100644
--- a/chrome/browser/extensions/extension_gcm_app_handler.cc
+++ b/chrome/browser/extensions/extension_gcm_app_handler.cc
@@ -53,7 +53,9 @@ ExtensionGCMAppHandler::ExtensionGCMAppHandler(content::BrowserContext* context)
   js_event_router_.reset(new extensions::GcmJsEventRouter(profile_));
 }
 
-ExtensionGCMAppHandler::~ExtensionGCMAppHandler() {
+ExtensionGCMAppHandler::~ExtensionGCMAppHandler() = default;
+
+void ExtensionGCMAppHandler::Shutdown() {
   const ExtensionSet& enabled_extensions =
       ExtensionRegistry::Get(profile_)->enabled_extensions();
   for (ExtensionSet::const_iterator extension = enabled_extensions.begin();