Introducing the WebServiceWorkerCacheStorage.

public/platform/WebServiceWorker.h

Index: public/platform/WebServiceWorker.h
diff --git a/public/platform/WebServiceWorker.h b/public/platform/WebServiceWorker.h
index 52ad440463796cc4c865bee1001d530c5a31e237..ee5448fd7ac9f2fe4cccc2e5b4c9f1c00693588c 100644
--- a/public/platform/WebServiceWorker.h
+++ b/public/platform/WebServiceWorker.h
@@ -40,6 +40,7 @@
 
 namespace blink {
 
+class WebServiceWorkerCacheStorage;
 class WebServiceWorkerProxy;
 typedef WebVector<class WebMessagePortChannel*> WebMessagePortChannelArray;
 
@@ -47,9 +48,13 @@ class WebServiceWorker {
 public:
     virtual ~WebServiceWorker() { }
 
-    // Sets ServiceWorkerProxy, with which callee can start making upcalls
-    // to the ServiceWorker object via the client. This doesn't pass the
-    // ownership to the callee, and the proxy's lifetime is same as that of
+    // Provides an implementation of the WebCacheStorage API to blink from the
+    // embedder.
+    virtual WebServiceWorkerCacheStorage* cacheStorage() { return 0; }
+
+    // Sets ServiceWorkerProxy, with which callee can start making upcalls to
+    // the ServiceWorker object via the client. This doesn't pass the ownership
+    // to the callee, and the proxy's lifetime is same as that of
     // WebServiceWorker.
     virtual void setProxy(WebServiceWorkerProxy*) { }
     virtual WebServiceWorkerProxy* proxy() { return 0; }