Set SkipServiceWorker flag in DocumentThreadableLoader::loadActualRequest().

third_party/WebKit/Source/core/loader/DocumentThreadableLoader.cpp

Index: third_party/WebKit/Source/core/loader/DocumentThreadableLoader.cpp
diff --git a/third_party/WebKit/Source/core/loader/DocumentThreadableLoader.cpp b/third_party/WebKit/Source/core/loader/DocumentThreadableLoader.cpp
index da915d21d032729966820a9096c2b0a6427a90c8..8502e4b3e5ee2aa623430bb3177ee2daf4678638 100644
--- a/third_party/WebKit/Source/core/loader/DocumentThreadableLoader.cpp
+++ b/third_party/WebKit/Source/core/loader/DocumentThreadableLoader.cpp
@@ -806,6 +806,12 @@ void DocumentThreadableLoader::loadActualRequest()
 
     clearResource();
 
+    // Explicitly set the SkipServiceWorker flag here. Even if the page was not
+    // controlled by a SW when the preflight request was sent, a new SW may be
+    // controlling the page now by calling clients.claim(). We should not send
+    // the actual request to the SW. https://crbug.com/604583
+    actualRequest.setSkipServiceWorker(true);

[tyoshino (SeeGerritForStatus), 2016/05/10 09:17:01]

So, the approach is to have the series of requests following a request which has
been handled without SW?

As I chatted offline, I'm guessing that similar issue may happen in following
redirect chain.

This code change looks good, but shouldn't we just mark the request in
DocumentThreadableLoader::start() so that it and its child requests never go
through SW?

[horo, 2016/05/10 13:20:27]

In the redirect case, the request is passed from
WebURLLoaderImpl::Context::OnReceivedRedirect() to
DocumentThreadableLoader::redirectReceived(). The SkipServiceWorker flag of the
request must be true if the page was not controlled by a SW when the first
request was sent. So I think there is no problem in the redirect case.

(And also we can't simply set the flag in DocumentThreadableLoader::start()
because the flag must be false when the request is for SharedWorker script and
ServiceWorker script and the scripts imported from those workers.)

[tyoshino (SeeGerritForStatus), 2016/05/10 13:52:48]

ok

+
     loadRequest(actualRequest, actualOptions);
     // |this| may be dead here in async mode.
 }