Have panels respond to changes in work area on Linux.

views/widget/native_widget_gtk.cc

Index: views/widget/native_widget_gtk.cc
diff --git a/views/widget/native_widget_gtk.cc b/views/widget/native_widget_gtk.cc
index c7ef5e209fe819bf33d5dcb6fd60804ec6735dcc..4a8e7add86289913dea3b30201e55859035b1606 100644
--- a/views/widget/native_widget_gtk.cc
+++ b/views/widget/native_widget_gtk.cc
@@ -26,6 +26,7 @@
 #include "ui/base/gtk/gtk_windowing.h"
 #include "ui/base/gtk/scoped_handle_gtk.h"
 #include "ui/base/hit_test.h"
+#include "ui/base/x/active_window_watcher_x.h"
 #include "ui/base/x/x11_util.h"
 #include "ui/gfx/canvas_skia_paint.h"
 #include "ui/gfx/compositor/compositor.h"
@@ -560,7 +561,7 @@ void NativeWidgetGtk::GetRequestedSize(gfx::Size* out) const {
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-// NativeWidgetGtk, ActiveWindowWatcherX::Observer implementation:
+// NativeWidgetGtk, ActiveWindowWatcherXObserver implementation:
 
 void NativeWidgetGtk::ActiveWindowChanged(GdkWindow* active_window) {
   if (!GetNativeView())