Introduce DeclarativeUserScriptManager.

extensions/browser/mock_extension_system.cc

Index: extensions/browser/mock_extension_system.cc
diff --git a/extensions/browser/mock_extension_system.cc b/extensions/browser/mock_extension_system.cc
index 94771d8a6fefa3dad54e2a1ceaf2fb64f0a89c67..b22b0d105820f9a524172221b368ee67dca5ac48 100644
--- a/extensions/browser/mock_extension_system.cc
+++ b/extensions/browser/mock_extension_system.cc
@@ -34,6 +34,11 @@ SharedUserScriptMaster* MockExtensionSystem::shared_user_script_master() {
   return nullptr;
 }
 
+DeclarativeUserScriptManager*
+MockExtensionSystem::declarative_user_script_manager() {
+  return nullptr;
+}
+
 StateStore* MockExtensionSystem::state_store() {
   return nullptr;
 }
@@ -74,12 +79,6 @@ ContentVerifier* MockExtensionSystem::content_verifier() {
   return nullptr;
 }
 
-DeclarativeUserScriptMaster*
-      MockExtensionSystem::GetDeclarativeUserScriptMasterByExtension(
-          const ExtensionId& extension_id) {
-  return nullptr;
-}
-
 scoped_ptr<ExtensionSet> MockExtensionSystem::GetDependentExtensions(
     const Extension* extension) {
   return scoped_ptr<ExtensionSet>();