If keysym is ASCII control or space keys, directly map to keycode.

ui/events/keycodes/keyboard_code_conversion_x.cc

Index: ui/events/keycodes/keyboard_code_conversion_x.cc
diff --git a/ui/events/keycodes/keyboard_code_conversion_x.cc b/ui/events/keycodes/keyboard_code_conversion_x.cc
index a4a810e23a43004eb09af168daa797968e6d8a23..88bcc441e96275da298ac71c9219944a6c6c5175 100644
--- a/ui/events/keycodes/keyboard_code_conversion_x.cc
+++ b/ui/events/keycodes/keyboard_code_conversion_x.cc
@@ -459,6 +459,12 @@ KeyboardCode FindVK(const T_MAP& key, const T_MAP* map, size_t size) {
   return VKEY_UNKNOWN;
 }
 
+bool IsAsciiControlKey(KeySym keysym) {
+  if ((keysym > 0xff00 && keysym < 0xff1f) || keysym == XK_Delete)

[Yuki, 2014/10/23 07:13:56]

keysym <= 0xff1f ?
I think we'd like to include 0xff1f, too.

We may want to comment that 0xff01 to 0xff1f represent ASCII control in keysym
world (it's not 0x01 to 0x1f).  It's not so trivial.  For example, XK_space is
0x20.  Not everyone knows Xkeysym details.

nit:
return (0xff01 <= keysym && keysym <= 0xff1f) || keysym == XK_Delete;
seems more natural to me, but it's up to you.

[Shu Chen, 2014/10/23 07:44:33]

Done.

+    return true;
+  return false;
+}
+
 }  // namespace
 
 // Get an ui::KeyboardCode from an X keyevent
@@ -492,7 +498,8 @@ KeyboardCode KeyboardCodeFromXKeyEvent(const XEvent* xev) {
   XLookupString(xkey, NULL, 0, &keysym, NULL);
   if (IsKeypadKey(keysym) || IsPrivateKeypadKey(keysym) ||
       IsCursorKey(keysym) || IsPFKey(keysym) || IsFunctionKey(keysym) ||
-      IsModifierKey(keysym)) {
+      IsModifierKey(keysym) || IsAsciiControlKey(keysym) ||
+      keysym == XK_space) {
     return KeyboardCodeFromXKeysym(keysym);
   }