Implement the infrastructure of creating WorkerFetchContext in worker global scope.

third_party/WebKit/public/web/WebSharedWorker.h

Index: third_party/WebKit/public/web/WebSharedWorker.h
diff --git a/third_party/WebKit/public/web/WebSharedWorker.h b/third_party/WebKit/public/web/WebSharedWorker.h
index 8f3179bda5b5a65f620ea8b4531910891b974cb5..5ded52738ac57a2a0783560c6ed8570846684fd4 100644
--- a/third_party/WebKit/public/web/WebSharedWorker.h
+++ b/third_party/WebKit/public/web/WebSharedWorker.h
@@ -39,6 +39,7 @@ namespace blink {
 
 class WebString;
 class WebMessagePortChannel;
+class WebServiceWorkerNetworkProvider;
 class WebSharedWorkerClient;
 class WebURL;
 
@@ -73,6 +74,8 @@ class WebSharedWorker {
                                        int call_id,
                                        const WebString& method,
                                        const WebString& message) = 0;
+  virtual WebServiceWorkerNetworkProvider*
+  GetServiceWorkerNetworkProvider() = 0;
 };
 
 }  // namespace blink