aura: A few changes to have aura_demo compile and run on linux.

ui/gfx/screen_aura.cc

Index: ui/gfx/screen_aura.cc
diff --git a/ui/gfx/screen_aura.cc b/ui/gfx/screen_aura.cc
index 75b0afcfd771119df0a6bbb0720606b8c62e20a3..b47a832fac696e84e0e03db2a7167286106f19d0 100644
--- a/ui/gfx/screen_aura.cc
+++ b/ui/gfx/screen_aura.cc
@@ -4,7 +4,9 @@
 
 #include "ui/gfx/screen.h"
 
+#if defined(OS_WIN)
 #include <windows.h>
+#endif
 
 #include "base/logging.h"
 
@@ -17,6 +19,8 @@ gfx::Point Screen::GetCursorScreenPoint() {
   GetCursorPos(&pt);
   return gfx::Point(pt);
 #endif
+  NOTIMPLEMENTED();
+  return gfx::Point();
 }
 
 // static