Remove the sender_id from the Push API code path.

content/renderer/push_messaging_dispatcher.cc

Index: content/renderer/push_messaging_dispatcher.cc
diff --git a/content/renderer/push_messaging_dispatcher.cc b/content/renderer/push_messaging_dispatcher.cc
index 1be95bd0b1119031c46329d90910bd0d39693eed..e699a309f9ad3d8ccaad48bf33c5742916babe83 100644
--- a/content/renderer/push_messaging_dispatcher.cc
+++ b/content/renderer/push_messaging_dispatcher.cc
@@ -41,16 +41,20 @@ void PushMessagingDispatcher::registerPushMessaging(
     const WebString& sender_id,
     blink::WebPushRegistrationCallbacks* callbacks,
     blink::WebServiceWorkerProvider* service_worker_provider) {
+  registerPushMessaging(callbacks, service_worker_provider);
+}
+
+void PushMessagingDispatcher::registerPushMessaging(
+    blink::WebPushRegistrationCallbacks* callbacks,
+    blink::WebServiceWorkerProvider* service_worker_provider) {
   RenderFrameImpl::FromRoutingID(routing_id())->manifest_manager()->GetManifest(
       base::Bind(&PushMessagingDispatcher::DoRegister,
                  base::Unretained(this),
-                 sender_id.utf8(),
                  callbacks,
                  service_worker_provider));
 }
 
 void PushMessagingDispatcher::DoRegister(
-    const std::string& sender_id,
     blink::WebPushRegistrationCallbacks* callbacks,
     blink::WebServiceWorkerProvider* service_worker_provider,
     const Manifest& manifest) {
@@ -62,7 +66,7 @@ void PushMessagingDispatcher::DoRegister(
       routing_id(),
       callbacks_id,
       manifest.gcm_sender_id.is_null()
-          ? sender_id
+          ? std::string()
           : base::UTF16ToUTF8(manifest.gcm_sender_id.string()),
       blink::WebUserGestureIndicator::isProcessingUserGesture(),
       service_worker_provider_id));