[WIP] [service worker] Fix detach controller and fallback to network mechanism

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

Index: third_party/WebKit/Source/core/fetch/ResourceLoader.cpp
diff --git a/third_party/WebKit/Source/core/fetch/ResourceLoader.cpp b/third_party/WebKit/Source/core/fetch/ResourceLoader.cpp
index 298d331b6ea6bdd11abe7e15130e9182471260ab..07ae611f8070b8522df548b7a989be2a323745a7 100644
--- a/third_party/WebKit/Source/core/fetch/ResourceLoader.cpp
+++ b/third_party/WebKit/Source/core/fetch/ResourceLoader.cpp
@@ -334,32 +334,39 @@ void ResourceLoader::didReceiveResponse(WebURLLoader*, const WebURLResponse& res
     const ResourceResponse& resourceResponse = response.toResourceResponse();
     TRACE_EVENT1("devtools.timeline", "ResourceReceiveResponse", "data", InspectorReceiveResponseEvent::data(m_resource->identifier(), resourceResponse));
 
-    if (responseNeedsAccessControlCheck()) {
-        if (response.wasFetchedViaServiceWorker()) {
-            if (response.wasFallbackRequiredByServiceWorker()) {
+    if (response.wasFetchedViaServiceWorker()) {
+        if (response.wasFallbackRequiredByServiceWorker()) {
+            // Fallback can be required in two cases:
+            // 1) The SW let a cross-origin request fallback to network. In that
+            // case, retry the request without the SW if CORS was enabled;
+            // otherwise, fail the request as disallowed.
+            // 2) The browser failed to dispatch the main resource request to
+            // the SW. In that case, retry the request without the SW.
+            if (responseNeedsAccessControlCheck() || m_resource->type() == Resource::MainResource) {
                 m_loader->cancel();
                 m_loader.clear();
                 m_connectionState = ConnectionStateStarted;
                 m_loader = adoptPtr(Platform::current()->createURLLoader());
                 ASSERT(m_loader);
-                ASSERT(!m_request.skipServiceWorker());
+                // skipServiceWorker can be true if this request was redirected.
+                // ASSERT(!m_request.skipServiceWorker());

[falken, 2015/11/26 10:36:42]

This ASSERT is probably meaning to say "we must not have already tried to fall
back". However, skipServiceWorker is set for any redirect in
WebURLLoaderImpl::PopulateURLRequestForRedirect. This is actually misleading
because it looks like the skip flag doesn't have an affect for main resource
redirects: it's only looked at in ResourceHostMsg_RequestResource (which
subresource redirects use) but not used in ResourceHostMsg_FollowRedirect (which
main resource redirects use).

                 m_request.setSkipServiceWorker(true);
                 WrappedResourceRequest wrappedRequest(m_request);
                 m_loader->loadAsynchronously(wrappedRequest, this);
                 return;
             }
-        } else {
-            // If the response successfully validated a cached resource, perform
-            // the access control with respect to it. Need to do this right here
-            // before the resource switches clients over to that validated resource.
-            Resource* resource = m_resource;
-            if (!resource->isCacheValidator() || resourceResponse.httpStatusCode() != 304)
-                m_resource->setResponse(resourceResponse);
-            if (!m_fetcher->canAccessResource(resource, m_options.securityOrigin.get(), response.url(), ResourceFetcher::ShouldLogAccessControlErrors)) {
-                m_fetcher->didReceiveResponse(m_resource, resourceResponse);
-                cancel(ResourceError::cancelledDueToAccessCheckError(KURL(response.url())));
-                return;
-            }
+        }
+    } else if (responseNeedsAccessControlCheck()) {
+        // If the response successfully validated a cached resource, perform
+        // the access control with respect to it. Need to do this right here
+        // before the resource switches clients over to that validated resource.
+        Resource* resource = m_resource;
+        if (!resource->isCacheValidator() || resourceResponse.httpStatusCode() != 304)
+            m_resource->setResponse(resourceResponse);
+        if (!m_fetcher->canAccessResource(resource, m_options.securityOrigin.get(), response.url(), ResourceFetcher::ShouldLogAccessControlErrors)) {
+            m_fetcher->didReceiveResponse(m_resource, resourceResponse);
+            cancel(ResourceError::cancelledDueToAccessCheckError(KURL(response.url())));
+            return;
         }
     }