Add Hide to app menu.

apps/app_shim/app_shim_messages.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.
 
 // Multiply-included message file, hence no include guard.
 
 #include <string>
 
 #include "apps/app_shim/app_shim_launch.h"
 #include "base/files/file_path.h"
 #include "ipc/ipc_message_macros.h"
 #include "ipc/param_traits_macros.h"
 
 #define IPC_MESSAGE_START AppShimMsgStart
 
 IPC_ENUM_TRAITS_MAX_VALUE(apps::AppShimLaunchType,
                           apps::APP_SHIM_LAUNCH_NUM_TYPES - 1)
 IPC_ENUM_TRAITS_MAX_VALUE(apps::AppShimLaunchResult,
                           apps::APP_SHIM_LAUNCH_NUM_RESULTS - 1)
 IPC_ENUM_TRAITS_MAX_VALUE(apps::AppShimFocusType,
                           apps::APP_SHIM_FOCUS_NUM_TYPES - 1)
 
 // Signals that a previous LaunchApp message has been processed, and lets the
 // app shim process know whether it was registered successfully.
 IPC_MESSAGE_CONTROL1(AppShimMsg_LaunchApp_Done,
                      apps::AppShimLaunchResult /* launch result */)
 
+// Instructs the shim to hide the app.
+IPC_MESSAGE_CONTROL0(AppShimMsg_Hide)
+
 // Instructs the shim to request user attention.
 IPC_MESSAGE_CONTROL0(AppShimMsg_RequestUserAttention)
 
 // Signals to the main Chrome process that a shim has started indicating the
 // profile and app_id that the shim should be associated with and whether to
 // launch the app immediately.
 IPC_MESSAGE_CONTROL3(AppShimHostMsg_LaunchApp,
                      base::FilePath /* profile dir */,
                      std::string /* app id */,
                      apps::AppShimLaunchType /* launch type */)
 
 // Sent when the user has indicated a desire to focus the app, either by
 // clicking on the app's icon in the dock or by selecting it with Cmd+Tab. In
 // response, Chrome brings the app's windows to the foreground, or relaunches
 // if the focus type indicates a reopen and there are no open windows.
 IPC_MESSAGE_CONTROL1(AppShimHostMsg_FocusApp,
                      apps::AppShimFocusType /* focus type */)
 
 // Sent when the app shim is hidden or unhidden.
 IPC_MESSAGE_CONTROL1(AppShimHostMsg_SetAppHidden,
                      bool /* hidden */)
 
 // Sent when the shim process receives a request to terminate. Once all of the
 // app's windows have closed, and the extension is unloaded, the AppShimHost
 // closes the channel. The shim process then completes the terminate request
 // and exits.
 IPC_MESSAGE_CONTROL0(AppShimHostMsg_QuitApp)