Start app shim when app launched.

apps/app_shim/app_shim_launch.h

+// 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 APPS_APP_SHIM_APP_SHIM_LAUNCH_H_
+#define APPS_APP_SHIM_APP_SHIM_LAUNCH_H_
+
+#include "ipc/ipc_param_traits.h"
+
+namespace apps {
+
+enum AppShimLaunchType {
+  REGISTER_WITHOUT_LAUNCH = 0,  // Process the app shim's LaunchApp message and

[tapted, 2013/05/30 03:25:06]

It's typical for enum values to share a common prefix (or suffix). Maybe 

APP_SHIM_LAUNCH_REGISTER_ONLY
APP_SHIM_LAUNCH_REGULAR

with the leading `APP_` perhaps optional, since it's a bit redundant with the
namespace.

[jackhou1, 2013/05/30 05:10:05]

Done.

But _NORMAL instead of _REGULAR, because it looks less like REGISTER.

+                                // associate the shim with the given profile
+                                // and app id.
+  LAUNCH_NOW,                   // Do the above and launch the app.
+};
+
+}  // namespace apps
+
+namespace IPC {
+
+template <>
+struct IPC::SimilarTypeTraits<apps::AppShimLaunchType> {
+  typedef int Type;
+};
+
+}  // namespace IPC
+
+#endif  // APPS_APP_SHIM_APP_SHIM_LAUNCH_H_