[ServiceWorker] Make fetch() method better conformance with the spec.

Source/core/fetch/ResourceFetcher.cpp

Index: Source/core/fetch/ResourceFetcher.cpp
diff --git a/Source/core/fetch/ResourceFetcher.cpp b/Source/core/fetch/ResourceFetcher.cpp
index 6b2bfe97fc9e3b61441668040af29eb7048911f6..7bffc2eec7b0c451888741edc3e6fca478f178e5 100644
--- a/Source/core/fetch/ResourceFetcher.cpp
+++ b/Source/core/fetch/ResourceFetcher.cpp
@@ -1299,7 +1299,14 @@ void ResourceFetcher::willSendRequest(unsigned long identifier, ResourceRequest&
 
 void ResourceFetcher::didReceiveResponse(const Resource* resource, const ResourceResponse& response)
 {
-    // FIXME: When response.wasFetchedViaServiceWorker() is true, we need to check the URL of the responce for CSP and CORS.
+    // If the response is fetched via ServiceWorker, the original URL of the response could be different from the URL of the request.
+    if (response.wasFetchedViaServiceWorker()) {
+        if (!canRequest(resource->type(), resource->lastResourceRequest().requestContext(), response.url(), resource->options(), false, FetchRequest::UseDefaultOriginRestrictionForType)) {
+            resource->loader()->cancel();
+            context().dispatchDidFail(m_documentLoader, resource->identifier(), ResourceError(errorDomainBlinkInternal, 0, response.url().string(), "Original url check of ServiceWorker fetched resource failed."));

[jochen (gone - plz use gerrit), 2014/07/24 14:37:26]

the error message would leave me a bit confused about what actually went wrong.
Can we do better?

[horo, 2014/07/24 15:50:22]

Done.

+            return;
+        }
+    }
     context().dispatchDidReceiveResponse(m_documentLoader, resource->identifier(), response, resource->loader());
 }