aura: Add X11 host window management.

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index cb4133f26b6150c3be25f20261eef52e3830c9cc..041a2da2152782f45e552b32b992c3a760c29547 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -25,6 +25,9 @@ class CommandLine;
 namespace aura {
 class EventFilter;
 class FocusManager;
+#if defined(USE_X11)
+class HostWindowManagerX11;
+#endif
 class RootWindow;
 class Window;
 namespace client {
@@ -81,6 +84,7 @@ class CaptureController;
 class DragDropController;
 class EventRewriterEventFilter;
 class FocusCycler;
+class HostWindowManager;
 class MagnificationController;
 class DisplayController;
 class MouseCursorEventFilter;
@@ -391,6 +395,11 @@ class ASH_EXPORT Shell : aura::CursorDelegate {
 
   ScreenAsh* screen_;
 
+  scoped_ptr<internal::HostWindowManager> host_window_manager_;
+#if defined(USE_X11)
+  scoped_ptr<aura::HostWindowManagerX11> x11_host_window_manager_;
+#endif
+
   // Active root window. Never become NULL.
   aura::RootWindow* active_root_window_;