Giving focus to an app shim brings windows belonging to that app to the foreground.

chrome/app/chrome_main_app_mode_mac.mm

Index: chrome/app/chrome_main_app_mode_mac.mm
diff --git a/chrome/app/chrome_main_app_mode_mac.mm b/chrome/app/chrome_main_app_mode_mac.mm
index a75f38da0fc895a5ae0c5ed6dd30226ff37594b7..f4a4134a46bb4fb343c7992ef36916dc5cf17319 100644
--- a/chrome/app/chrome_main_app_mode_mac.mm
+++ b/chrome/app/chrome_main_app_mode_mac.mm
@@ -51,6 +51,7 @@ class AppShimController : public IPC::Listener {
   // shim process should die.
   void OnLaunchAppDone(bool success);
 
+  void OnDidActivateApplicationNotification(NSNotification* notification);

[koz (OOO until 15th September), 2013/03/18 03:33:12]

comment and newline after this

[jeremya, 2013/03/18 04:54:05]

Done, plus changed the function to only be called when the notification refers
to this application.

   // Quits the app shim process.
   void Quit();
 
@@ -95,14 +96,31 @@ void AppShimController::OnChannelError() {
 }
 
 void AppShimController::OnLaunchAppDone(bool success) {
-  if (!success)
+  if (!success) {
     Quit();
+    return;
+  }
+  [[[NSWorkspace sharedWorkspace] notificationCenter]
+      addObserverForName:NSWorkspaceDidActivateApplicationNotification
+                  object:nil
+                   queue:nil
+              usingBlock:^(NSNotification* notification) {
+    OnDidActivateApplicationNotification(notification);
+  }];
 }
 
 void AppShimController::Quit() {
   [NSApp terminate:nil];
 }
 
+void AppShimController::OnDidActivateApplicationNotification(
+    NSNotification* notification) {
+  NSRunningApplication* activated_app =
+      [[notification userInfo] objectForKey:NSWorkspaceApplicationKey];
+  if ([activated_app isEqual:[NSRunningApplication currentApplication]])
+    channel_->Send(new AppShimHostMsg_FocusApp);
+}
+
 //-----------------------------------------------------------------------------
 
 // A ReplyEventHandler is a helper class to send an Apple Event to a process