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

extensions/renderer/extension_injection_host.cc

 // 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.
 
+#include "extensions/common/extension_set.h"
 #include "extensions/common/manifest_handlers/csp_info.h"
 #include "extensions/renderer/extension_injection_host.h"
 
 namespace extensions {
 
 ExtensionInjectionHost::ExtensionInjectionHost(
-    const scoped_refptr<const Extension>& extension)
+    const Extension* extension)
     : InjectionHost(HostID(HostID::EXTENSIONS, extension->id())),
       extension_(extension) {
 }
 
 ExtensionInjectionHost::~ExtensionInjectionHost() {
 }
 
-const std::string& ExtensionInjectionHost::GetContentSecurityPolicy() const {
-  return CSPInfo::GetContentSecurityPolicy(extension_.get());
+// static
+scoped_ptr<const ExtensionInjectionHost> ExtensionInjectionHost::Create(
+    const std::string& extension_id, const ExtensionSet* extensions) {
+  const Extension* extension = extensions->GetByID(extension_id);
+  if (!extension)
+    return scoped_ptr<const ExtensionInjectionHost>();
+  return scoped_ptr<const ExtensionInjectionHost>(
+      new ExtensionInjectionHost(extension));
+}
+
+std::string ExtensionInjectionHost::GetContentSecurityPolicy() const {
+  return CSPInfo::GetContentSecurityPolicy(extension_);
 }
 
 const GURL& ExtensionInjectionHost::url() const {
   return extension_->url();
 }
 
 const std::string& ExtensionInjectionHost::name() const {
   return extension_->name();
 }
 
 PermissionsData::AccessType ExtensionInjectionHost::CanExecuteOnFrame(
       const GURL& document_url,
       const GURL& top_frame_url,
       int tab_id,
       bool is_declarative) const {
   // Declarative user scripts use "page access" (from "permissions" section in
   // manifest) whereas non-declarative user scripts use custom
   // "content script access" logic.
   if (is_declarative) {
     return extension_->permissions_data()->GetPageAccess(
-        extension_.get(),
+        extension_,
         document_url,
         top_frame_url,
         tab_id,
         -1,  // no process id
         nullptr /* ignore error */);
   } else {
     return extension_->permissions_data()->GetContentScriptAccess(
-        extension_.get(),
+        extension_,
         document_url,
         top_frame_url,
         tab_id,
         -1,  // no process id
         nullptr /* ignore error */);
   }
 }
 
 bool ExtensionInjectionHost::ShouldNotifyBrowserOfInjection() const {
   // We notify the browser of any injection if the extension has no withheld
   // permissions (i.e., the permissions weren't restricted), but would have
   // otherwise been affected by the scripts-require-action feature.
   return extension_->permissions_data()->withheld_permissions()->IsEmpty() &&
          PermissionsData::ScriptsMayRequireActionForExtension(
-             extension_.get(),
+             extension_,
              extension_->permissions_data()->active_permissions().get());
 }
 
 }  // namespace extensions