Patch on top of https://codereview.chromium.org/433793002/

Source/modules/serviceworkers/Request.h

Index: Source/modules/serviceworkers/Request.h
diff --git a/Source/modules/serviceworkers/Request.h b/Source/modules/serviceworkers/Request.h
index eafb73f6a8e01d96c9d7c73b83d370a02c4ce5a4..7069524696545ebc5757d7aa27591de58a0a867a 100644
--- a/Source/modules/serviceworkers/Request.h
+++ b/Source/modules/serviceworkers/Request.h
@@ -28,11 +28,12 @@ class Request FINAL : public GarbageCollected<Request>, public ScriptWrappable {
 public:
     static Request* create(ExecutionContext*, const String&, ExceptionState&);
     static Request* create(ExecutionContext*, const String&, const Dictionary&, ExceptionState&);
-    static Request* create(ExecutionContext*, Request*, ExceptionState&);
-    static Request* create(ExecutionContext*, Request*, const Dictionary&, ExceptionState&);
+    static Request* create(ExecutionContext*, const Request*, ExceptionState&);
+    static Request* create(ExecutionContext*, const Request*, const Dictionary&, ExceptionState&);
     static Request* create(FetchRequestData*);
     static Request* create(const WebServiceWorkerRequest&);
 
+    const FetchRequestData* request() const { return m_request; }
     FetchRequestData* request() { return m_request; }
 
     String method() const;
@@ -43,7 +44,7 @@ public:
     String mode() const;
     String credentials() const;
 
-    void populateWebServiceWorkerRequest(WebServiceWorkerRequest&);
+    void populateWebServiceWorkerRequest(WebServiceWorkerRequest&) const;
 
     void setBodyBlobHandle(PassRefPtr<BlobDataHandle>);