Introduce HostID and de-couple Extensions from "script injection System" [browser side]

extensions/renderer/user_script_injector.cc

 // 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.
 
 #include "extensions/renderer/user_script_injector.h"
 
 #include <vector>
 
 #include "base/lazy_instance.h"
 #include "content/public/common/url_constants.h"
@@ skipping 42 matching lines @@
     LAZY_INSTANCE_INITIALIZER;
 
 }  // namespace
 
 UserScriptInjector::UserScriptInjector(
     const UserScript* script,
     UserScriptSet* script_list,
     bool is_declarative)
     : script_(script),
       script_id_(script_->id()),
-      extension_id_(script_->extension_id()),
+      extension_id_(script_->GetExtensionID()),
       is_declarative_(is_declarative),
       user_script_set_observer_(this) {
   user_script_set_observer_.Add(script_list);
 }
 
 UserScriptInjector::~UserScriptInjector() {
 }
 
 void UserScriptInjector::OnUserScriptsUpdated(
     const std::set<std::string>& changed_extensions,
@@ skipping 146 matching lines @@
   }
 
   if (ShouldInjectCss(run_location))
     scripts_run_info->num_css += script_->css_scripts().size();
 }
 
 void UserScriptInjector::OnWillNotInject(InjectFailureReason reason) {
 }
 
 }  // namespace extensions