Pipe the FirstPartyForCookies to WorkerFetchContext for off-main-thread-fetch

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

Index: third_party/WebKit/Source/core/loader/ThreadableLoadingContext.cpp
diff --git a/third_party/WebKit/Source/core/loader/ThreadableLoadingContext.cpp b/third_party/WebKit/Source/core/loader/ThreadableLoadingContext.cpp
index 551dd18c046896d657658ce0ba857ba03f1f5304..e5f4ef6cd05ecb34006802cf3e09ae128ccd631e 100644
--- a/third_party/WebKit/Source/core/loader/ThreadableLoadingContext.cpp
+++ b/third_party/WebKit/Source/core/loader/ThreadableLoadingContext.cpp
@@ -101,9 +101,7 @@ class WorkerThreadableLoadingContext : public ThreadableLoadingContext {
 
   KURL FirstPartyForCookies() const override {
     DCHECK(IsContextThread());
-    // TODO(horo): Returns the FirstPartyForCookies of the parent frame for
-    // dedicated workers.
-    return worker_global_scope_->Url();
+    return fetch_context_->FirstPartyForCookies();
   }
 
   String UserAgent() const override {