Have panels respond to changes in work area on Linux.

ui/base/x/active_window_watcher_x_observer.h

Index: ui/base/x/active_window_watcher_x_observer.h
diff --git a/ui/base/x/active_window_watcher_x_observer.h b/ui/base/x/active_window_watcher_x_observer.h
new file mode 100644
index 0000000000000000000000000000000000000000..834e6da5a6da13524f26276b44af807e7a195a29
--- /dev/null
+++ b/ui/base/x/active_window_watcher_x_observer.h
@@ -0,0 +1,26 @@
+// 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.
+
+#ifndef UI_BASE_X_ACTIVE_WINDOW_WATCHER_X_OBSERVER_H_
+#define UI_BASE_X_ACTIVE_WINDOW_WATCHER_X_OBSERVER_H_
+#pragma once
+
+#include <gdk/gdk.h>
+
+#include "ui/base/ui_export.h"
+
+namespace ui {
+
+class UI_EXPORT ActiveWindowWatcherXObserver {
+ public:
+  // |active_window| will be NULL if the active window isn't one of Chrome's.
+  virtual void ActiveWindowChanged(GdkWindow* active_window) = 0;
+
+ protected:
+  virtual ~ActiveWindowWatcherXObserver();

[sky, 2011/11/21 23:50:32]

You can inline this. By that I mean put the {} right here. Inlining destructors
of pure virtual classes is one the exceptions to not inlining in headers.

[prasadt, 2011/11/22 00:46:34]

Done.

+};
+
+}  // namespace ui
+
+#endif  // UI_BASE_X_ACTIVE_WINDOW_WATCHER_X_OBSERVER_H_