Extract input_method_whitelist.{h|cc} from c/b/chromeos.

chromeos/ime/input_methods.txt

 # The list of input methods that we support. The input methods metadata is
 # also defined here. We use this data for the following purposes.
 #
 # 1. Exclude unnecessary input methods. For example, we don't need
 #    "ja:anthy", and "zh:pinyin" engines in ibus-m17n since we have better
 #    alternatives outside of ibus-m17n. Excluding these input methods from
 #    the IBus engine XML files, such as /usr/share/ibus/component/m17n.xml,
 #    makes the startup time of the IBus daemon faster. This filtering is
 #    done using a python script at build time of ibus-m17n.
 #    See crosbug.com/4161 for details.
@@ skipping 31 matching lines @@
 #
 # Notes:
 #   When adding a line to this list, please also add a mapping from the input
 #   method ID to the keyboard overlay ID to INPUT_METHOD_ID_TO_OVERLAY_ID in
 #
 #    * tools/gen_keyboard_overlay_data/gen_keyboard_overlay_data.py
 #
 #   and update the following files by running this script.
 #
 #    * chrome/app/generated_resources.grd
-#    * chrome/browser/resources/keyboard_overlay_data.js
+#    * chrome/browser/resources/chromeos/keyboard_overlay_data.js
 #    * chrome/browser/ui/webui/chromeos/keyboard_overlay_ui.cc
 #
 #   If you add an XKB layout which depends on X11's Mod3Mask (e.g. Germany Neo2
 #   XKB layout), you should also update IsMod3UsedByCurrentInputMethod() method
 #   in chrome/browser/ui/ash/event_rewriter.cc. Otherwise, Mod3Mask might be
 #   removed unexpectedly by the rewriter.
 
 # U.S. English
 xkb:us::eng     us      en-US
 xkb:us:intl:eng us(intl)        en-US   
@@ skipping 140 matching lines @@
 xkb:pt::por     pt      pt-PT   
 xkb:ro::rum     ro      ro      
 xkb:se::swe     se      sv      
 xkb:sk::slo     sk      sk      
 xkb:si::slv     si      sl      
 xkb:rs::srp     rs      sr      
 xkb:tr::tur     tr      tr      
 xkb:ua::ukr     ua      uk      
 # TODO(yusukes): Support xkb:latam:deadtilde:spa and/or xkb:latam:nodeadkeys:spa
 # if necessary.