Add blink-side plumbing for ServiceWorker -> Document postMessage (1/3)

public/platform/WebServiceWorkerProviderClient.h

Index: public/platform/WebServiceWorkerProviderClient.h
diff --git a/public/platform/WebServiceWorkerProviderClient.h b/public/platform/WebServiceWorkerProviderClient.h
index c38a9965b045bfd8249ae8ba42f0fffe70c79203..8c3eba3f59336040c081b84f8b64b300880aa6dc 100644
--- a/public/platform/WebServiceWorkerProviderClient.h
+++ b/public/platform/WebServiceWorkerProviderClient.h
@@ -31,6 +31,8 @@
 #ifndef WebServiceWorkerProviderClient_h
 #define WebServiceWorkerProviderClient_h
 
+#include "public/platform/WebMessagePortChannel.h"
+
 namespace blink {
 class WebServiceWorker;
 class WebString;
@@ -43,6 +45,8 @@ public:
 
     // The callee will take ownership of the given WebServiceWorker object.
     virtual void setCurrentServiceWorker(WebServiceWorker*) = 0;
+
+    virtual void dispatchMessageEvent(const WebString& message, const WebMessagePortChannelArray&) = 0;
 };
 
 };