[ServiceWorker] Convert ping-pong IPC into mojo interface ServiceWorkerEventDispatcher

content/common/service_worker/service_worker_messages.h

Index: content/common/service_worker/service_worker_messages.h
diff --git a/content/common/service_worker/service_worker_messages.h b/content/common/service_worker/service_worker_messages.h
index 7cc0eee78e53b6ab84f15780c829c07858a99941..9c75a89adc69a100d04743a1cef46d63db260c93 100644
--- a/content/common/service_worker/service_worker_messages.h
+++ b/content/common/service_worker/service_worker_messages.h
@@ -251,10 +251,6 @@ IPC_MESSAGE_ROUTED4(ServiceWorkerHostMsg_FetchEventResponse,
                     content::ServiceWorkerResponse,
                     base::Time /* dispatch_event_time */)
 
-// Responds to a Ping from the browser.
-// Routed to the target ServiceWorkerVersion.
-IPC_MESSAGE_ROUTED0(ServiceWorkerHostMsg_Pong)
-
 // Asks the browser to retrieve client of the sender ServiceWorker.
 IPC_MESSAGE_ROUTED2(ServiceWorkerHostMsg_GetClient,
                     int /* request_id */,
@@ -490,9 +486,6 @@ IPC_MESSAGE_CONTROL3(ServiceWorkerMsg_ClaimClientsError,
                      blink::WebServiceWorkerError::ErrorType /* code */,
                      base::string16 /* message */)
 
-// Sent via EmbeddedWorker to Ping the worker, expecting a Pong in response.
-IPC_MESSAGE_CONTROL0(ServiceWorkerMsg_Ping)
-
 // Sent via EmbeddedWorker as a response of GetClient.
 IPC_MESSAGE_CONTROL2(ServiceWorkerMsg_DidGetClient,
                      int /* request_id */,