Make win_aura work without ash.

ui/aura/root_window_host_linux.cc

Index: ui/aura/root_window_host_linux.cc
===================================================================
--- ui/aura/root_window_host_linux.cc	(revision 134107)
+++ ui/aura/root_window_host_linux.cc	(working copy)
@@ -594,6 +594,10 @@
   root_window_ = root_window;
 }
 
+RootWindow* RootWindowHostLinux::GetRootWindow() {
+  return root_window_;
+}
+
 gfx::AcceleratedWidget RootWindowHostLinux::GetAcceleratedWidget() {
   return xwindow_;
 }
@@ -800,6 +804,13 @@
 }
 
 // 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));