Revert of Use a token to initialise ChannelMojo and MojoApplication everywhere.

content/common/mojo/channel_init.h

+// Copyright 2015 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 CONTENT_COMMON_MOJO_CHANNEL_INIT_H_
+#define CONTENT_COMMON_MOJO_CHANNEL_INIT_H_
+
+#include "base/files/file.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "content/common/content_export.h"
+#include "mojo/public/cpp/system/message_pipe.h"
+
+namespace base {
+class TaskRunner;
+}
+
+namespace content {
+
+// ChannelInit handles creation and destruction of the Mojo channel. It is not
+// thread-safe, but may be used on any single thread with a MessageLoop.
+//
+// TODO(rockot): Get rid of this class ASAP (i.e. once the patch which includes
+// this TODO has stuck for a bit) since it's no longer necessary.
+class CONTENT_EXPORT ChannelInit {
+ public:
+  ChannelInit();
+  ~ChannelInit();
+
+  // Initializes the channel. This takes ownership of |file|.
+  mojo::ScopedMessagePipeHandle Init(
+      base::PlatformFile file,
+      scoped_refptr<base::TaskRunner> io_thread_task_runner);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ChannelInit);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_COMMON_MOJO_CHANNEL_INIT_H_