Introduce DeclarativeUserScriptManager.

extensions/browser/mock_extension_system.h

Index: extensions/browser/mock_extension_system.h
diff --git a/extensions/browser/mock_extension_system.h b/extensions/browser/mock_extension_system.h
index 8eb9a484161fc7fd5a7ae99e2f96a252840ea34a..f28a292331dbf77a03365bece98ba536dc0f28a1 100644
--- a/extensions/browser/mock_extension_system.h
+++ b/extensions/browser/mock_extension_system.h
@@ -33,6 +33,7 @@ class MockExtensionSystem : public ExtensionSystem {
   RuntimeData* runtime_data() override;
   ManagementPolicy* management_policy() override;
   SharedUserScriptMaster* shared_user_script_master() override;
+  DeclarativeUserScriptManager* declarative_user_script_manager() override;
   StateStore* state_store() override;
   StateStore* rules_store() override;
   InfoMap* info_map() override;
@@ -45,8 +46,6 @@ class MockExtensionSystem : public ExtensionSystem {
   ContentVerifier* content_verifier() override;
   scoped_ptr<ExtensionSet> GetDependentExtensions(
       const Extension* extension) override;
-  DeclarativeUserScriptMaster* GetDeclarativeUserScriptMasterByExtension(
-      const ExtensionId& extension_id) override;
 
  private:
   content::BrowserContext* browser_context_;