mojo: Fix running view-manager related apptests on X11.

ui/platform_window/x11/x11_window.h

Index: ui/platform_window/x11/x11_window.h
diff --git a/ui/platform_window/x11/x11_window.h b/ui/platform_window/x11/x11_window.h
index b964b89476c2701349b6223654a7d542c63c86bc..5e0a2c3050e21dd08922a0762807bdb6778f5c44 100644
--- a/ui/platform_window/x11/x11_window.h
+++ b/ui/platform_window/x11/x11_window.h
@@ -66,6 +66,11 @@ class X11_WINDOW_EXPORT X11Window : public PlatformWindow,
   DISALLOW_COPY_AND_ASSIGN(X11Window);
 };
 
+namespace test {
+X11_WINDOW_EXPORT void SetUseOverrideRedirectWindowByDefault(

[msw, 2015/07/16 19:17:50]

Can you add an explanatory comment here? Even after reading
https://tronche.com/gui/x/xlib/window/attributes/override-redirect.html I don't
fully understand the functionality of XSetWindowAttributes::override_redirect
(or the reasoning for setting it).

[sadrul, 2015/07/16 19:57:14]

Added a comment. This is fairly voodoo, and might very well depend on the
particular window-manager/x-server.

+    bool override_redirect);
+}  // namespace test
+
 }  // namespace ui
 
 #endif  // UI_PLATFORM_WINDOW_X11_X11_WINDOW_H_