Fix use-after-free in WidgetCaptureTest.SetCaptureToNonToplevel.

ui/views/widget/widget_interactive_uitest.cc

 // Copyright (c) 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 <stddef.h>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/location.h"
 #include "base/macros.h"
@@ skipping 1539 matching lines @@
 #if defined(OS_MACOSX) && !defined(USE_AURA)
   // On Mac, activation is asynchronous. A single trip to the runloop should be
   // sufficient. On Aura platforms, note that since the child widget isn't top-
   // level, the aura window manager gets asked whether the widget is active, not
   // the OS.
   base::RunLoop().RunUntilIdle();
 #endif
 
   EXPECT_TRUE(observer.activation_observed());
   EXPECT_TRUE(child->HasCapture());
+
+  child->RemoveObserver(&observer);
 }
 
 
 #if defined(OS_WIN)
 namespace {
 
 // Used to verify OnMouseEvent() has been invoked.
 class MouseEventTrackingWidget : public Widget {
  public:
   MouseEventTrackingWidget() : got_mouse_event_(false) {}
@@ skipping 252 matching lines @@
 
   ui::KeyEvent key_event2(key_event);
   widget->OnKeyEvent(&key_event2);
   EXPECT_FALSE(key_event2.stopped_propagation());
 
   widget->CloseNow();
 }
 
 }  // namespace test
 }  // namespace views