Do not reuse opaque Resource from a service worker for non no-cors requests

third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp

Index: third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp
diff --git a/third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp b/third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp
index b57c1bbef3c98a2d53991cb54263394cad756c5c..4782123a83bdcdf1939b19800291a725e09ccf12 100644
--- a/third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp
+++ b/third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp
@@ -690,6 +690,11 @@ ResourceFetcher::RevalidationPolicy ResourceFetcher::determineRevalidationPolicy
     if (request.downloadToFile() || request.useStreamOnResponse())
         return Reload;
 
+    // Never reuse opaque responses from a service worker for requests that
+    // are not no-cors. https://crbug.com/625575
+    if (existingResource->response().wasFetchedViaServiceWorker() && existingResource->response().serviceWorkerResponseType() == WebServiceWorkerResponseTypeOpaque && request.fetchRequestMode() != WebURLRequest::FetchRequestModeNoCORS)
+        return Reload;
+
     // If resource was populated from a SubstituteData load or data: url, use it.
     if (isStaticData)
         return Use;