Start app shim when app launched.

apps/app_shim/app_shim_messages.h

Index: apps/app_shim/app_shim_messages.h
diff --git a/apps/app_shim/app_shim_messages.h b/apps/app_shim/app_shim_messages.h
index 6a6cc6d07a88f25a95c0d55b77931c41c1faa938..136d961677ff60a38f173ced02f2afe3b32f21b7 100644
--- a/apps/app_shim/app_shim_messages.h
+++ b/apps/app_shim/app_shim_messages.h
@@ -11,15 +11,17 @@
 #define IPC_MESSAGE_START AppShimMsgStart
 
 // Signals that a previous LaunchApp message has been processed, and lets the
-// app shim process know whether the app launch was successful.
+// app shim process know whether it was registered successfully.
 IPC_MESSAGE_CONTROL1(AppShimMsg_LaunchApp_Done,
                      bool /* succeeded */)
 
-// Tells the main Chrome process to launch a particular app with the given
-// profile name and app id.
-IPC_MESSAGE_CONTROL2(AppShimHostMsg_LaunchApp,
+// 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,
                      std::string /* profile name */,
-                     std::string /* app id */)
+                     std::string /* app id */,
+                     bool /* launch now */)
 
 // 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