[Extensions] Make UserScriptInjector's script update stricter

extensions/renderer/user_script_set.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_SET_H_
 #define EXTENSIONS_RENDERER_USER_SCRIPT_SET_H_
 
 #include <memory>
 #include <set>
 #include <string>
@@ skipping 14 matching lines @@
 namespace extensions {
 class ScriptInjection;
 
 // The UserScriptSet is a collection of UserScripts which knows how to update
 // itself from SharedMemory and create ScriptInjections for UserScripts to
 // inject on a page.
 class UserScriptSet {
  public:
   class Observer {
    public:
+    // Called when the set of user scripts is updated. |changed_hosts| contains
+    // the hosts whose scripts have been altered. Note that *all* script objects
+    // are invalidated, even if they aren't in |changed_hosts|.
     virtual void OnUserScriptsUpdated(const std::set<HostID>& changed_hosts,
                                       const UserScriptList& scripts) = 0;
   };
 
   UserScriptSet();
   ~UserScriptSet();
 
   // Adds or removes observers.
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
@@ skipping 45 matching lines @@
 
   // The associated observers.
   base::ObserverList<Observer> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(UserScriptSet);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_USER_SCRIPT_SET_H_