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

ui/aura/event_filter.cc

Index: ui/aura/event_filter.cc
diff --git a/ui/aura/event_filter.cc b/ui/aura/event_filter.cc
index 68748fbe3dafdec09654e804d12ee94651a1cae6..41436b3c1c090ff00d9aea8d40fa98e436f32f19 100644
--- a/ui/aura/event_filter.cc
+++ b/ui/aura/event_filter.cc
@@ -4,6 +4,10 @@
 
 #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) {
@@ -13,6 +17,11 @@ 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;
 }