[ServiceWorker] Make Request class better conformance with the spec.

public/platform/WebServiceWorkerRequest.h

Index: public/platform/WebServiceWorkerRequest.h
diff --git a/public/platform/WebServiceWorkerRequest.h b/public/platform/WebServiceWorkerRequest.h
index c0544afcc5a625f9b70a31aa393cbf99c976c272..058a38b1f5984302836e081a3cc13382a42bdadb 100644
--- a/public/platform/WebServiceWorkerRequest.h
+++ b/public/platform/WebServiceWorkerRequest.h
@@ -12,8 +12,9 @@
 
 #if INSIDE_BLINK
 #include "wtf/Forward.h"
-#include "wtf/HashMap.h"
+#include "wtf/Vector.h"
 #include "wtf/text/StringHash.h"
+#include <utility>
 #endif
 
 namespace blink {
@@ -44,11 +45,15 @@ public:
 
     void setHeader(const WebString& key, const WebString& value);
 
+    void setReferrer(const WebString&);
+    WebString referrer() const;
+
     void setIsReload(bool);
     bool isReload() const;
 
 #if INSIDE_BLINK
-    const HashMap<String, String>& headers() const;
+    typedef std::pair<String, String> Header;
+    const Vector<OwnPtr<Header> >& headerList() const;
 #endif
 
 private: