Remove InsecureContentInfobarDelegate, which has been broken for a while

chrome/renderer/content_settings_observer.h

 // Copyright (c) 2012 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_RENDERER_CONTENT_SETTINGS_OBSERVER_H_
 #define CHROME_RENDERER_CONTENT_SETTINGS_OBSERVER_H_
 
 #include <map>
 #include <set>
 
@@ skipping 82 matching lines @@
 
   // RenderFrameObserver implementation.
   bool OnMessageReceived(const IPC::Message& message) override;
   void DidCommitProvisionalLoad(bool is_new_navigation,
                                 bool is_same_page_navigation) override;
   void OnDestruct() override;
 
   // Message handlers.
   void OnLoadBlockedPlugins(const std::string& identifier);
   void OnSetAsInterstitial();
-  void OnSetAllowDisplayingInsecureContent(bool allow);
   void OnSetAllowRunningInsecureContent(bool allow);
   void OnReloadFrame();
   void OnRequestFileSystemAccessAsyncResponse(int request_id, bool allowed);
 
   // Resets the |content_blocked_| array.
   void ClearBlockedContentSettings();
 
   // Whether the observed RenderFrame is for a platform app.
   bool IsPlatformApp();
 
@@ skipping 44 matching lines @@
   typedef std::map<int, blink::WebContentSettingCallbacks> PermissionRequestMap;
   PermissionRequestMap permission_requests_;
 
   // If true, IsWhitelistedForContentSettings will always return true.
   const bool should_whitelist_;
 
   DISALLOW_COPY_AND_ASSIGN(ContentSettingsObserver);
 };
 
 #endif  // CHROME_RENDERER_CONTENT_SETTINGS_OBSERVER_H_