NOT FOR COMMIT: POC of using AuthenticatingURLLoader in Sky

sky/engine/public/platform/Platform.h

Index: sky/engine/public/platform/Platform.h
diff --git a/sky/engine/public/platform/Platform.h b/sky/engine/public/platform/Platform.h
index e39689508c05dcec27e1f0b1bdf822ed90e2365e..e385ee5c99862ff939fe6a6b4231af1efcbe0ae4 100644
--- a/sky/engine/public/platform/Platform.h
+++ b/sky/engine/public/platform/Platform.h
@@ -47,6 +47,7 @@ class SingleThreadTaskRunner;
 }
 
 namespace mojo {
+class AuthenticatingURLLoaderFactory;
 class NetworkService;
 }
 
@@ -151,6 +152,11 @@ public:
 
     virtual mojo::NetworkService* networkService() { return 0; }
 
+    virtual mojo::AuthenticatingURLLoaderFactory*
+    authenticatingURLLoaderFactory() {
+      return 0;
+    }
+
     // Returns a new WebURLLoader instance.
     virtual WebURLLoader* createURLLoader() { return 0; }