[ios] Added web// public API to let embedder observe loading progress.

ios/web/public/test/test_web_state.h

Index: ios/web/public/test/test_web_state.h
diff --git a/ios/web/public/test/test_web_state.h b/ios/web/public/test/test_web_state.h
index b189298dc8a17e4f59c74e3d17b16d64c2639870..e510f8fb35aeb5414ad4e9ea65a28ae72b9911cf 100644
--- a/ios/web/public/test/test_web_state.h
+++ b/ios/web/public/test/test_web_state.h
@@ -24,6 +24,8 @@ class TestWebState : public WebState {
 
   // WebState implementation.
   UIView* GetView() override;
+  WebStateDelegate* GetDelegate() override;
+  void SetDelegate(WebStateDelegate* delegate) override;
   WebViewType GetWebViewType() const override;
   BrowserState* GetBrowserState() const override;
   void OpenURL(const OpenURLParams& params) override {}