Add a CodeToNativeKeycode helper that converts UIEvent code to native code.

ui/base/keycodes/usb_keycode_map.h

Index: ui/base/keycodes/usb_keycode_map.h
diff --git a/ui/base/keycodes/usb_keycode_map.h b/ui/base/keycodes/usb_keycode_map.h
index 90cd7ed71723e4ba6dcdb3ecb9248bac942140bd..1ebbbbbb3fdbd1ea1e6dec3db5f94239c1d49910 100644
--- a/ui/base/keycodes/usb_keycode_map.h
+++ b/ui/base/keycodes/usb_keycode_map.h
@@ -399,6 +399,17 @@ inline const char* NativeKeycodeToCode(uint16_t native_keycode) {
   return InvalidKeyboardEventCode();
 }
 
+inline uint16_t CodeToNativeKeycode(const char* code) {
+  if (code) {

[Wez, 2013/09/05 00:16:33]

You don't need this if - the loop will exit on the first iteration if |code| is
NULL.

[Wez, 2013/09/05 00:16:33]

You should explicitly check for "Unidentified" here, and return
InvalidNativeKeycode() in that case, otherwise you scan the entire array only to
find no match.

[weitao, 2013/09/05 07:49:17]

I do need this "if". Otherwise strcmp would crash.

[Wez, 2013/09/05 19:07:02]

Yes, sorry; missed that you're not comparing the ptr value in the loop. ;)

+    // TODO: sort |usb_keycode_map| by |code| so we can use binary search here.

[Wez, 2013/09/05 00:16:33]

This comment assumes that linear search performance won't be sufficient; if you
want to research that, please file a bug rather than adding a comment here. :)

[weitao, 2013/09/05 07:49:17]

Done.

+    for (size_t i = 0; i < arraysize(usb_keycode_map); ++i) {
+      if (usb_keycode_map[i].code && strcmp(usb_keycode_map[i].code, code) == 0)

[Wez, 2013/09/05 00:16:33]

Split this into two if()s for clarity.

[weitao, 2013/09/05 07:49:17]

I feel the purpose of two conditions connected by && is pretty clear; if the
current code is not NULL and it equals the code passed in. The first condition
is necessary because strcmp requires non-NULL arguments.

[Wez, 2013/09/05 19:07:02]

Right - I'm suggesting:

if (!code)
  continue;
if (strcmp)
  return stuff;

+        return usb_keycode_map[i].native_keycode;
+    }
+  }
+  return InvalidNativeKeycode();
+}
+
 // USB keycodes
 // Note that USB keycodes are not part of any web standard.
 // Please don't use USB keycodes in new code.