Avoid showing the supervised user block interstitial more than once

chrome/browser/supervised_user/supervised_user_interstitial.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 CHROME_BROWSER_SUPERVISED_USER_SUPERVISED_USER_INTERSTITIAL_H_
 #define CHROME_BROWSER_SUPERVISED_USER_SUPERVISED_USER_INTERSTITIAL_H_
 
 #include <string>
 
 #include "base/callback.h"
@@ skipping 33 matching lines @@
 
  private:
   SupervisedUserInterstitial(
       content::WebContents* web_contents,
       const GURL& url,
       supervised_user_error_page::FilteringBehaviorReason reason,
       bool initial_page_load,
       const base::Callback<void(bool)>& callback);
   ~SupervisedUserInterstitial() override;
 
-  bool Init();
+  void Init();
 
   // InterstitialPageDelegate implementation.
   std::string GetHTMLContents() override;
   void CommandReceived(const std::string& command) override;
   void OnProceed() override;
   void OnDontProceed() override;
   content::InterstitialPageDelegate::TypeID GetTypeForTesting() const override;
 
   // SupervisedUserServiceObserver implementation.
   void OnURLFilterChanged() override;
@@ skipping 30 matching lines @@
   bool initial_page_load_;
 
   base::Callback<void(bool)> callback_;
 
   base::WeakPtrFactory<SupervisedUserInterstitial> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SupervisedUserInterstitial);
 };
 
 #endif  // CHROME_BROWSER_SUPERVISED_USER_SUPERVISED_USER_INTERSTITIAL_H_