Create ExtensionsRendererClient.

extensions/renderer/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/extensions_renderer_client.h"
+
+#include "base/basictypes.h"
+
+namespace extensions {
+
+namespace {
+
+ExtensionsRendererClient* g_client = NULL;
+
+}  // namespace
+
+ExtensionsRendererClient* ExtensionsRendererClient::Get() { return g_client; }
+
+void ExtensionsRendererClient::Set(ExtensionsRendererClient* client) {
+  g_client = client;
+}
+
+}  // namespace extensions