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

apps/app_shim/app_shim_host_mac.cc

 // 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.
 
 #include "apps/app_shim/app_shim_host_mac.h"
 
 #include "apps/app_shim/app_shim_messages.h"
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/extensions/extension_host.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/extension_system.h"
 #include "chrome/browser/extensions/shell_window_registry.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/ui/extensions/application_launch.h"
+#include "chrome/browser/ui/extensions/shell_window.h"
 #include "chrome/common/extensions/extension_constants.h"
 #include "ipc/ipc_channel_proxy.h"
+#include "ui/base/cocoa/focus_window_set.h"
 
 AppShimHost::AppShimHost()
     : channel_(NULL), profile_(NULL) {
 }
 
 AppShimHost::~AppShimHost() {
   DCHECK(CalledOnValidThread());
 }
 
 void AppShimHost::ServeChannel(const IPC::ChannelHandle& handle) {
   DCHECK(CalledOnValidThread());
   DCHECK(!channel_.get());
   channel_.reset(new IPC::ChannelProxy(handle, IPC::Channel::MODE_SERVER, this,
       BrowserThread::GetMessageLoopProxyForThread(BrowserThread::IO)));
 }
 
 bool AppShimHost::OnMessageReceived(const IPC::Message& message) {
   DCHECK(CalledOnValidThread());
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(AppShimHost, message)
     IPC_MESSAGE_HANDLER(AppShimHostMsg_LaunchApp, OnLaunchApp)
+    IPC_MESSAGE_HANDLER(AppShimHostMsg_FocusApp, OnFocus)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
 
   return handled;
 }
 
 bool AppShimHost::Send(IPC::Message* message) {
   DCHECK(channel_.get());
   return channel_->Send(message);
 }
 
 void AppShimHost::OnLaunchApp(std::string profile_dir, std::string app_id) {
   DCHECK(CalledOnValidThread());
   bool success = LaunchAppImpl(profile_dir, app_id);
   Send(new AppShimMsg_LaunchApp_Done(success));
 }
 
+void AppShimHost::OnFocus() {
+  DCHECK(CalledOnValidThread());
+  if (!profile_)
+    return;
+  extensions::ShellWindowRegistry* registry =
+      extensions::ShellWindowRegistry::Get(profile_);
+  const std::set<ShellWindow*> windows =
+      registry->GetShellWindowsForApp(app_id_);
+  std::set<gfx::NativeWindow> native_windows;
+  for (std::set<ShellWindow*>::const_iterator i = windows.begin();
+       i != windows.end();
+       ++i) {
+    native_windows.insert((*i)->GetNativeWindow());
+  }
+  ui::FocusWindowSet(native_windows);
+}
+
 bool AppShimHost::LaunchAppImpl(const std::string& profile_dir,
                                 const std::string& app_id) {
   DCHECK(CalledOnValidThread());
   if (profile_) {
     // Only one app launch message per channel.
     return false;
   }
   if (!extensions::Extension::IdIsValid(app_id)) {
     LOG(ERROR) << "Bad app ID from app shim launch message.";
     return false;
@@ skipping 76 matching lines @@
     default:
       NOTREACHED() << "Unexpected notification sent.";
       break;
   }
 }
 
 void AppShimHost::Close() {
   DCHECK(CalledOnValidThread());
   delete this;
 }