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 aba263d5cb7b3445563896e24b5ab1465a614c63..104f36bd8048b7ac1107fb458d576171d6e446c8 100644
--- a/third_party/WebKit/Source/core/loader/DocumentThreadableLoader.cpp
+++ b/third_party/WebKit/Source/core/loader/DocumentThreadableLoader.cpp
@@ -789,6 +789,12 @@ 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);
+
     loadRequest(actualRequest, actualOptions);
     // |this| may be dead here in async mode.
 }