Stop saving the request to |fallback_request_for_service_worker_| in ThreadableLoader.

Stop saving the request if OutOfBlinkCors is enabled.
This is because |fallback_request_for_service_worker_|
is needed only when OutOfBlinkCors is disabled.

Bug: 787704
Change-Id: Idae728e80f4b229b236790494b61c28687fdbb6b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2128004
Commit-Queue: Yoichi Osato <yoichio@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Reviewed-by: Takashi Toyoshima <toyoshim@chromium.org>
Reviewed-by: Tsuyoshi Horo <horo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#760387}

third_party/blink/renderer/core/loader/threadable_loader.cc

@@ -319,7 +319,8 @@ void ThreadableLoader::Start(const ResourceRequest& request) {
     return;
   }
 
-  if (cors::IsCorsEnabledRequestMode(request.GetMode())) {
+  if (!out_of_blink_cors_ &&
+      cors::IsCorsEnabledRequestMode(request.GetMode())) {
     // Save the request to fallback_request_for_service_worker to use when the
     // service worker doesn't handle (call respondWith()) a CORS enabled
     // request.

third_party/blink/renderer/core/loader/threadable_loader.h

@@ -218,7 +218,7 @@ class CORE_EXPORT ThreadableLoader final
   const ResourceLoaderOptions resource_loader_options_;
 
   // True when feature OutOfBlinkCors is enabled (https://crbug.com/736308).
-  bool out_of_blink_cors_;
+  const bool out_of_blink_cors_;
 
   // Corresponds to the CORS flag in the Fetch spec.
   bool cors_flag_ = false;