[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 d3f6772566a8a13f7fc1f355f5ad65f9342f2cf1..126a418eca2c82db7e5605892302551778de42d6 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;
   BrowserState* GetBrowserState() const override;
   void OpenURL(const OpenURLParams& params) override {}
   NavigationManager* GetNavigationManager() override;