Refactoring: de-couple Extensions from "script injection System" [render side]:3

extensions/renderer/extension_injection_host.h

 // Copyright 2015 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 EXTENSIONS_RENDERER_EXTENSION_INJECTION_HOST_H_
 #define EXTENSIONS_RENDERER_EXTENSION_INJECTION_HOST_H_
 
 #include "base/memory/ref_counted.h"
 #include "extensions/common/extension.h"
 #include "extensions/renderer/injection_host.h"
 
 namespace extensions {
 
 // A wrapper class that holds an extension and implements the InjectionHost
 // interface.
 class ExtensionInjectionHost : public InjectionHost {
  public:
   ExtensionInjectionHost(const scoped_refptr<const Extension>& extension);
   ~ExtensionInjectionHost() override;
 
  private:
   // InjectionHost:
-  const std::string& GetContentSecurityPolicy() const override;
+  std::string GetContentSecurityPolicy() const override;
   const GURL& url() const override;
   const std::string& name() const override;
   PermissionsData::AccessType CanExecuteOnFrame(
       const GURL& document_url,
       const GURL& top_frame_url,
       int tab_id,
       bool is_declarative) const override;
+  bool IsGone() const override;
 
   scoped_refptr<const Extension> extension_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionInjectionHost);
 };
 
 }  // namespace extesions
 
 #endif  // EXTENSIONS_RENDERER_EXTENSION_INJECTION_HOST_H_