Move URL Loader creation to a separate factory object.

mojo/shell/network_fetcher.h

Index: mojo/shell/network_fetcher.h
diff --git a/mojo/shell/network_fetcher.h b/mojo/shell/network_fetcher.h
index 21fb143a4b7c884aeb87d3b08688080b2d91bcb8..5b9ab650e7cb8cfcfda8e70919fca9d96ad4def4 100644
--- a/mojo/shell/network_fetcher.h
+++ b/mojo/shell/network_fetcher.h
@@ -14,7 +14,7 @@
 
 namespace mojo {
 
-class NetworkService;
+class URLLoaderFactory;
 
 namespace shell {
 
@@ -23,7 +23,7 @@ class NetworkFetcher : public Fetcher {
  public:
   NetworkFetcher(bool disable_cache,
                  mojo::URLRequestPtr request,
-                 NetworkService* network_service,
+                 URLLoaderFactory* url_loader_factory,
                  const FetchCallback& loader_callback);
 
   ~NetworkFetcher() override;
@@ -65,7 +65,7 @@ class NetworkFetcher : public Fetcher {
   bool PeekFirstLine(std::string* line) override;
 
   void StartNetworkRequest(mojo::URLRequestPtr request,
-                           NetworkService* network_service);
+                           URLLoaderFactory* url_loader_factory);
 
   void OnLoadComplete(URLResponsePtr response);