Make DeclarativeUserScriptManager non-shared between profiles.

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 b22b0d105820f9a524172221b368ee67dca5ac48..a62a22280f06df731af11d3d0cb29ede88d26e42 100644
--- a/extensions/browser/mock_extension_system.cc
+++ b/extensions/browser/mock_extension_system.cc
@@ -34,11 +34,6 @@ SharedUserScriptMaster* MockExtensionSystem::shared_user_script_master() {
   return nullptr;
 }
 
-DeclarativeUserScriptManager*
-MockExtensionSystem::declarative_user_script_manager() {
-  return nullptr;
-}
-
 StateStore* MockExtensionSystem::state_store() {
   return nullptr;
 }