ServiceWorker: Add initial implementation of ExtendableMessageEvent behind a flag

content/browser/service_worker/service_worker_version.h

Index: content/browser/service_worker/service_worker_version.h
diff --git a/content/browser/service_worker/service_worker_version.h b/content/browser/service_worker/service_worker_version.h
index 9ac8315eabe0b1994c57253cc5c6f874c228dd01..c90a263fe8ce124612c4b31afe509be1ab56bc79 100644
--- a/content/browser/service_worker/service_worker_version.h
+++ b/content/browser/service_worker/service_worker_version.h
@@ -236,11 +236,22 @@ class CONTENT_EXPORT ServiceWorkerVersion
   void DispatchSimpleEvent(int request_id, const IPC::Message& message);
 
   // Sends a message event to the associated embedded worker.
+  // TODO(nhiroki): Remove this after ExtendableMessageEvent is enabled by
+  // default (crbug.com/543198).
   void DispatchMessageEvent(
       const base::string16& message,
       const std::vector<TransferredMessagePort>& sent_message_ports,
       const StatusCallback& callback);
 
+  // Sends an extendable message event to the associated embedded worker.
+  // TODO(nhiroki): This should be moved to ServiceWorkerDispatcherHost in favor
+  // of crbug.com/570820 after ExtendableMessageEvent is implemented
+  // (crbug.com/543198).
+  void DispatchExtendableMessageEvent(
+      const base::string16& message,
+      const std::vector<TransferredMessagePort>& sent_message_ports,
+      const StatusCallback& callback);
+
   // Sends install event to the associated embedded worker and asynchronously
   // calls |callback| when it errors out or it gets a response from the worker
   // to notify install completion.
@@ -538,6 +549,10 @@ class CONTENT_EXPORT ServiceWorkerVersion
 
   void DispatchInstallEventAfterStartWorker(const StatusCallback& callback);
   void DispatchActivateEventAfterStartWorker(const StatusCallback& callback);
+  void DispatchExtendableMessageEventAfterStartWorker(
+      const base::string16& message,
+      const std::vector<TransferredMessagePort>& sent_message_ports,
+      const StatusCallback& callback);
 
   void DispatchMessageEventInternal(
       const base::string16& message,