Add an API for hosted apps to check their install and running states.

chrome/common/extensions/extension_messages.h

 // Copyright (c) 2012 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.
 
 // IPC messages for extensions.
 // Multiply-included message file, hence no include guard.
 
 #include "base/shared_memory.h"
 #include "base/values.h"
 #include "chrome/common/extensions/extension.h"
@@ skipping 261 matching lines @@
                     int32 /* install id */,
                     bool /* whether the install was successful */,
                     std::string /* error */)
 
 // Response to the renderer for ExtensionHostMsg_GetAppNotifyChannel.
 IPC_MESSAGE_ROUTED3(ExtensionMsg_GetAppNotifyChannelResponse,
                     std::string /* channel_id */,
                     std::string /* error */,
                     int32 /* callback_id */)
 
+// Response to the renderer for ExtensionHostMsg_GetAppInstallState.
+IPC_MESSAGE_ROUTED2(ExtensionMsg_GetAppInstallStateResponse,
+                    std::string /* state */,
+                    int32 /* callback_id */)
+
 // Dispatch the Port.onConnect event for message channels.
 IPC_MESSAGE_ROUTED5(ExtensionMsg_DispatchOnConnect,
                     int /* target_port_id */,
                     std::string /* channel_name */,
                     std::string /* tab_json */,
                     std::string /* source_extension_id */,
                     std::string /* target_extension_id */)
 
 // Deliver a message sent with ExtensionHostMsg_PostMessage.
 IPC_MESSAGE_ROUTED2(ExtensionMsg_DeliverMessage,
@@ skipping 102 matching lines @@
                     GURL /* requestor URL */)
 
 // Sent by the renderer when an App is requesting permission to send server
 // pushed notifications.
 IPC_MESSAGE_ROUTED4(ExtensionHostMsg_GetAppNotifyChannel,
                     GURL /* requestor_url */,
                     std::string /* client_id */,
                     int32 /* return_route_id */,
                     int32 /* callback_id */)
 
+// Sent by the renderer when a web page is checking if its app is installed.
+IPC_MESSAGE_ROUTED3(ExtensionHostMsg_GetAppInstallState,
+                    GURL /* requestor_url */,
+                    int32 /* return_route_id */,
+                    int32 /* callback_id */)
+
 // Optional Ack message sent to the browser to notify that the response to a
 // function has been processed.
 IPC_MESSAGE_ROUTED1(ExtensionHostMsg_ResponseAck,
                     int /* request_id */)
 
 // Response to ExtensionMsg_ShouldUnload.
 IPC_MESSAGE_CONTROL2(ExtensionHostMsg_ShouldUnloadAck,
                      std::string /* extension_id */,
                      int /* sequence_id */)
 
 // Response to ExtensionMsg_Unload, after we dispatch the unload event.
 IPC_MESSAGE_CONTROL1(ExtensionHostMsg_UnloadAck,
                      std::string /* extension_id */)
 
 // Informs the browser to increment the keepalive count for the lazy background
 // page, keeping it alive.
 IPC_MESSAGE_ROUTED0(ExtensionHostMsg_IncrementLazyKeepaliveCount)
 
 // Informs the browser there is one less thing keeping the lazy background page
 // alive.
 IPC_MESSAGE_ROUTED0(ExtensionHostMsg_DecrementLazyKeepaliveCount)
 
 // Fetches a globally unique ID (for the lifetime of the browser) from the
 // browser process.
 IPC_SYNC_MESSAGE_CONTROL0_1(ExtensionHostMsg_GenerateUniqueID,
                             int /* unique_id */)