Introduce a Gin class instead of using global functions to control gin

gin/initialize.h

Index: gin/initialize.h
diff --git a/gin/initialize.h b/gin/initialize.h
deleted file mode 100644
index 4ebcf8da48e1983fd1bf98290af45ed96af2991b..0000000000000000000000000000000000000000
--- a/gin/initialize.h
+++ /dev/null
@@ -1,14 +0,0 @@
-// Copyright 2013 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.
-
-#ifndef GIN_INITIALIZE_H_
-#define GIN_INITIALIZE_H_
-
-namespace gin {
-
-void Initialize();
-
-}  // namespace gin
-
-#endif  // GIN_INITIALIZE_H_