Fixes aura unit tests. There were a couple of problems:

ui/aura/event_filter.cc

 // Copyright (c) 2011 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 "ui/aura/event_filter.h"
 
+#include "ui/aura/event.h"
+#include "ui/aura/focus_manager.h"
+#include "ui/aura/window.h"
+
 namespace aura {
 
 EventFilter::EventFilter(Window* owner) : owner_(owner) {
 }
 
 EventFilter::~EventFilter() {
 }
 
 bool EventFilter::OnMouseEvent(Window* target, MouseEvent* event) {
+  if (event->type() == ui::ET_MOUSE_PRESSED) {
+    // TODO(beng): some windows (e.g. disabled ones, tooltips, etc) may not be
+    //             focusable.
+    target->GetFocusManager()->SetFocusedWindow(target);
+  }
   return false;
 }
 
 }  // namespace aura