Remove extension group from DOMWrapperWorld.

extensions/renderer/test_extensions_renderer_client.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/test_extensions_renderer_client.h"
 
 namespace extensions {
 
-TestExtensionsRendererClient::TestExtensionsRendererClient() {}
+TestExtensionsRendererClient::TestExtensionsRendererClient() {
+  ExtensionsRendererClient::Set(this);
+}
 
-TestExtensionsRendererClient::~TestExtensionsRendererClient() {}
+TestExtensionsRendererClient::~TestExtensionsRendererClient() {
+  ExtensionsRendererClient::Set(nullptr);
+}
 
 bool TestExtensionsRendererClient::IsIncognitoProcess() const {
   return false;
 }
 
 int TestExtensionsRendererClient::GetLowestIsolatedWorldId() const {
   // Note that 0 is reserved for the global world.
   return 1;
 }
 
 }  // namespace extensions