Add support for unregistering web intents default by service_url.

chrome/browser/intents/web_intents_registry.cc

Index: chrome/browser/intents/web_intents_registry.cc
diff --git a/chrome/browser/intents/web_intents_registry.cc b/chrome/browser/intents/web_intents_registry.cc
index 856fe3c991a9516a01d0de98a0be813d8afc9964..7afbd1cafba7c93c8dddffe0c5ce40742ef8004b 100644
--- a/chrome/browser/intents/web_intents_registry.cc
+++ b/chrome/browser/intents/web_intents_registry.cc
@@ -451,6 +451,11 @@ void WebIntentsRegistry::UnregisterDefaultIntentService(
   wds_->RemoveDefaultWebIntentService(default_service);
 }
 
+void WebIntentsRegistry::UnregisterServiceDefaults(const GURL& service_url) {
+  DCHECK(wds_.get());
+  wds_->RemoveWebIntentServiceDefaults(service_url);
+}
+
 void WebIntentsRegistry::GetDefaultIntentService(
     const string16& action,
     const string16& type,