Added const getter for WebState's NavigationManager.

ios/web/public/test/test_web_state.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef IOS_WEB_PUBLIC_TEST_TEST_WEB_STATE_H_
 #define IOS_WEB_PUBLIC_TEST_TEST_WEB_STATE_H_
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 12 matching lines @@
   ~TestWebState() override;
 
   // WebState implementation.
   WebStateDelegate* GetDelegate() override;
   void SetDelegate(WebStateDelegate* delegate) override;
   bool IsWebUsageEnabled() const override;
   void SetWebUsageEnabled(bool enabled) override;
   UIView* GetView() override;
   BrowserState* GetBrowserState() const override;
   void OpenURL(const OpenURLParams& params) override {}
+  const NavigationManager* GetNavigationManager() const override;
   NavigationManager* GetNavigationManager() override;
   CRWJSInjectionReceiver* GetJSInjectionReceiver() const override;
   void ExecuteJavaScript(const base::string16& javascript) override;
   void ExecuteJavaScript(const base::string16& javascript,
                          const JavaScriptResultCallback& callback) override;
   const std::string& GetContentsMimeType() const override;
   const std::string& GetContentLanguageHeader() const override;
   bool ContentIsHTML() const override;
   const base::string16& GetTitle() const override;
   bool IsLoading() const override;
@@ skipping 34 matching lines @@
   base::string16 title_;
   URLVerificationTrustLevel trust_level_;
   bool content_is_html_;
   std::string mime_type_;
   std::string content_language_;
 };
 
 }  // namespace web
 
 #endif  // IOS_WEB_PUBLIC_TEST_TEST_WEB_STATE_H_