Close all windows when app shim quits.

apps/app_shim/app_shim_host_mac.cc

Index: apps/app_shim/app_shim_host_mac.cc
diff --git a/apps/app_shim/app_shim_host_mac.cc b/apps/app_shim/app_shim_host_mac.cc
index ad63e93038ff20ad397037c5dbe7e262728ef63a..07c9903b6f2f320d05f3323b37d2aa9b01bb3d05 100644
--- a/apps/app_shim/app_shim_host_mac.cc
+++ b/apps/app_shim/app_shim_host_mac.cc
@@ -47,6 +47,7 @@ bool AppShimHost::OnMessageReceived(const IPC::Message& message) {
   IPC_BEGIN_MESSAGE_MAP(AppShimHost, message)
     IPC_MESSAGE_HANDLER(AppShimHostMsg_LaunchApp, OnLaunchApp)
     IPC_MESSAGE_HANDLER(AppShimHostMsg_FocusApp, OnFocus)
+    IPC_MESSAGE_HANDLER(AppShimHostMsg_QuitApp, OnQuit)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
 
@@ -85,6 +86,13 @@ void AppShimHost::OnFocus() {
     handler->OnShimFocus(this);
 }
 
+void AppShimHost::OnQuit() {
+  DCHECK(CalledOnValidThread());
+  apps::AppShimHandler* handler = apps::AppShimHandler::GetForAppMode(app_id_);
+  if (handler)
+    handler->OnShimQuit(this);
+}
+
 Profile* AppShimHost::FetchProfileForDirectory(const std::string& profile_dir) {
   ProfileManager* profileManager = g_browser_process->profile_manager();
   // Even though the name of this function is "unsafe", there's no security