aura: Introduce ScopedWindowTargeter.

It is sometimes necessary to temporary replace the event-targeter for a window,
and restore the previous event-targeter after some time. To that end, this patch
introduces ScopedWindowTargeter.

BUG=318879, 338671
R=ben@chromium.org

Review URL: https://codereview.chromium.org/135543004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248101 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 42 insertions, 0 deletions

diff --git a/ui/aura/scoped_window_targeter.h b/ui/aura/scoped_window_targeter.h
new file mode 100644
index 0000000..ce65092
--- /dev/null
+++ b/ui/aura/scoped_window_targeter.h
@@ -0,0 +1,42 @@
+// Copyright 2014 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.
+
+#ifndef UI_AURA_SCOPED_WINDOW_TARGETER_H_
+#define UI_AURA_SCOPED_WINDOW_TARGETER_H_
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "ui/aura/window_observer.h"
+
+namespace ui {
+class EventTargeter;
+}
+
+namespace aura {
+
+class Window;
+
+// ScopedWindowTargeter is used to temporarily replace the event-targeter for a
+// window. Upon construction, it installs a new targeter on the window, and upon
+// destruction, it restores the previous event-targeter on the window.
+class AURA_EXPORT ScopedWindowTargeter : public WindowObserver {
+ public:
+  ScopedWindowTargeter(Window* window,
+                       scoped_ptr<ui::EventTargeter> new_targeter);
+
+  virtual ~ScopedWindowTargeter();
+
+ private:
+  // WindowObserver:
+  virtual void OnWindowDestroyed(Window* window) OVERRIDE;
+
+  Window* window_;
+  scoped_ptr<ui::EventTargeter> old_targeter_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedWindowTargeter);
+};
+
+}  // namespace aura
+
+#endif  // UI_AURA_SCOPED_WINDOW_TARGETER_H_