Implement the infrastructure of creating WorkerFetchContext in worker global scope.

third_party/WebKit/Source/core/workers/WorkerGlobalScope.h

Index: third_party/WebKit/Source/core/workers/WorkerGlobalScope.h
diff --git a/third_party/WebKit/Source/core/workers/WorkerGlobalScope.h b/third_party/WebKit/Source/core/workers/WorkerGlobalScope.h
index 4abdcf3a14a0d988b58bf24be9f7ca31f141c76a..ec165161ef75c46579b4154b31888734fad4cb16 100644
--- a/third_party/WebKit/Source/core/workers/WorkerGlobalScope.h
+++ b/third_party/WebKit/Source/core/workers/WorkerGlobalScope.h
@@ -51,6 +51,7 @@ class ConsoleMessage;
 class ExceptionState;
 class V8AbstractEventListener;
 class WorkerClients;
+class WorkerFetchContext;
 class WorkerLocation;
 class WorkerNavigator;
 class WorkerThread;
@@ -153,6 +154,9 @@ class CORE_EXPORT WorkerGlobalScope
 
   WorkerClients* Clients() const { return worker_clients_.Get(); }
 
+  // Available only when off-main-thread-fetch is enabled.
+  WorkerFetchContext* GetFetchContext();
+
   DECLARE_VIRTUAL_TRACE();
 
  protected:
@@ -208,6 +212,8 @@ class CORE_EXPORT WorkerGlobalScope
 
   HeapHashMap<int, Member<ErrorEvent>> pending_error_events_;
   int last_pending_error_event_id_;
+
+  Member<WorkerFetchContext> fetch_context_;
 };
 
 DEFINE_TYPE_CASTS(WorkerGlobalScope,