Refactoring: de-couple Extensions from "script injection System" [render side]:4

extensions/renderer/user_script_injector.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 EXTENSIONS_RENDERER_USER_SCRIPT_INJECTOR_H_
 #define EXTENSIONS_RENDERER_USER_SCRIPT_INJECTOR_H_
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 14 matching lines @@
 class UserScriptInjector : public ScriptInjector,
                            public UserScriptSet::Observer {
  public:
   UserScriptInjector(const UserScript* user_script,
                      UserScriptSet* user_script_set,
                      bool is_declarative);
   ~UserScriptInjector() override;
 
  private:
   // UserScriptSet::Observer implementation.
-  void OnUserScriptsUpdated(const std::set<std::string>& changed_extensions,
+  void OnUserScriptsUpdated(const std::set<HostID>& changed_hosts,
                             const std::vector<UserScript*>& scripts) override;
 
   // ScriptInjector implementation.
   UserScript::InjectionType script_type() const override;
   bool ShouldExecuteInChildFrames() const override;
   bool ShouldExecuteInMainWorld() const override;
   bool IsUserGesture() const override;
   bool ExpectsResults() const override;
   bool ShouldInjectJs(UserScript::RunLocation run_location) const override;
   bool ShouldInjectCss(UserScript::RunLocation run_location) const override;
@@ skipping 14 matching lines @@
 
   // The associated user script. Owned by the UserScriptInjector that created
   // this object.
   const UserScript* script_;
 
   // The id of the associated user script. We cache this because when we update
   // the |script_| associated with this injection, the old referance may be
   // deleted.
   int script_id_;
 
-  // The associated extension id, preserved for the same reason as |script_id|.
-  std::string extension_id_;
+  // The associated host id, preserved for the same reason as |script_id|.
+  HostID host_id_;
 
   // Indicates whether or not this script is declarative. This influences which
   // script permissions are checked before injection.
   bool is_declarative_;
 
   ScopedObserver<UserScriptSet, UserScriptSet::Observer>
       user_script_set_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(UserScriptInjector);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_USER_SCRIPT_INJECTOR_H_