Make win_aura work without ash.

ui/aura/root_window_host_linux.cc

 // Copyright (c) 2012 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.
 
 #include "ui/aura/root_window_host_linux.h"
 
 #include <X11/Xatom.h>
 #include <X11/cursorfont.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/extensions/Xfixes.h>
@@ skipping 576 matching lines @@
       break;
     }
   }
   return true;
 }
 
 void RootWindowHostLinux::SetRootWindow(RootWindow* root_window) {
   root_window_ = root_window;
 }
 
+RootWindow* RootWindowHostLinux::GetRootWindow() {
+  return root_window_;
+}
+
 gfx::AcceleratedWidget RootWindowHostLinux::GetAcceleratedWidget() {
   return xwindow_;
 }
 
 void RootWindowHostLinux::Show() {
   // Before we map the window, set size hints. Otherwise, some window managers
   // will ignore toplevel XMoveWindow commands.
   XSizeHints size_hints;
   size_hints.flags = PPosition;
   size_hints.x = bounds_.x();
@@ skipping 186 matching lines @@
       ui::GetXCursor(CursorShapeFromNative(cursor));
   XDefineCursor(xdisplay_, xwindow_, xcursor);
 }
 
 // static
 RootWindowHost* RootWindowHost::Create(const gfx::Rect& bounds) {
   return new RootWindowHostLinux(bounds);
 }
 
 // static
+RootWindowHost* RootWindowHost::GetForAcceleratedWidget(
+    gfx::AcceleratedWidget accelerated_widget) {
+  NOTIMPLEMENTED();
+  return NULL;  // TODO(erg): implement if necessary or remove this comment.
+}
+
+// static
 gfx::Size RootWindowHost::GetNativeScreenSize() {
   ::Display* xdisplay = base::MessagePumpX::GetDefaultXDisplay();
   return gfx::Size(DisplayWidth(xdisplay, 0), DisplayHeight(xdisplay, 0));
 }
 
 }  // namespace aura