As for digits (native or not), there are interesting cases (serial number in hexadecimal,  passkey, passcode in decimal)


void BluetoothNotificationController::DisplayPasskey(BluetoothDevice* device,
                                                     uint32_t passkey) {
  base::string16 message = l10n_util::GetStringFUTF16(
          IDS_ASH_STATUS_TRAY_BLUETOOTH_DISPLAY_PASSKEY,
          device->GetName(), base::UTF8ToUTF16(
              base::StringPrintf("%06i", passkey)));

  NotifyPairing(device, message, false);
}

There are tons of StringPrintf with various format specifier. The vast majority of them are not used in the UI, though, but some of them might.

My number in comment 0 is a number of grd files with this issue ( < 20). The actual number of messages with '<ex>[0-9]+</ex>' is over 90 !  
Reviewing them all and fixing them take rather long (see bug 613347)

https://codereview.chromium.org/2002783002 : a first try (a partial fix).
 
There are more strings to review and fix if necessary. 

I left alone 'percent' because it's being taken care of by Greg elsewhere. 

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/bccecf36c6ae6bf612174eaaac7effec854877ee

commit bccecf36c6ae6bf612174eaaac7effec854877ee
Author: jshin <jshin@chromium.org>
Date: Fri Jun 03 02:59:58 2016

Use plural formats and native digits

With codesearch, look for '<ex>[0-9]+</ex> file:grd'. Review each of
matches and change them to use plural formats(C++), toLocaleString(JavaScript),
or other i18n-safe ways.

Moreover, change GetStringFUTF16Int() to use 'FormatNumber' instead
of Int*ToString(). Call sites of GetStringFUTF16Int() were reviewed
Where native digits are not appropriate (non-UI), call sites were
adjusted.

Besides, add a warning about 'ASCII digits vs native digits' to
base/strings/string_number_conversions.h and add more details
on GetPlural* to ui/base/l10n/l10n_util.h.

BUG= 613331 
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:closure_compilation;tryserver.blink:linux_blink_rel,mac_blink_rel

Review-Url: https://codereview.chromium.org/2002783002
Cr-Commit-Position: refs/heads/master@{#397608}

[modify] https://crrev.com/bccecf36c6ae6bf612174eaaac7effec854877ee/ash/system/chromeos/network/tray_sms.cc
[modify] https://crrev.com/bccecf36c6ae6bf612174eaaac7effec854877ee/base/strings/string_number_conversions.h
[modify] https://crrev.com/bccecf36c6ae6bf612174eaaac7effec854877ee/chrome/app/bookmarks_strings.grdp
[modify] https://crrev.com/bccecf36c6ae6bf612174eaaac7effec854877ee/chrome/app/generated_resources.grd
[modify] https://crrev.com/bccecf36c6ae6bf612174eaaac7effec854877ee/chrome/browser/media/desktop_media_list_ash.cc
[modify] https://crrev.com/bccecf36c6ae6bf612174eaaac7effec854877ee/chrome/browser/media/native_desktop_media_list.cc
[modify] https://crrev.com/bccecf36c6ae6bf612174eaaac7effec854877ee/chrome/browser/profiles/profile_attributes_storage.cc
[modify] https://crrev.com/bccecf36c6ae6bf612174eaaac7effec854877ee/chrome/browser/resources/history/history.js
[modify] https://crrev.com/bccecf36c6ae6bf612174eaaac7effec854877ee/chrome/browser/resources/history/other_devices.js
[modify] https://crrev.com/bccecf36c6ae6bf612174eaaac7effec854877ee/chrome/browser/resources/print_preview/settings/dpi_settings.js
[modify] https://crrev.com/bccecf36c6ae6bf612174eaaac7effec854877ee/chrome/browser/ui/android/content_settings/popup_blocked_infobar_delegate.cc
[modify] https://crrev.com/bccecf36c6ae6bf612174eaaac7effec854877ee/chrome/browser/ui/bookmarks/bookmark_utils_desktop.cc
[modify] https://crrev.com/bccecf36c6ae6bf612174eaaac7effec854877ee/components/crash/core/browser/resources/crashes.js
[modify] https://crrev.com/bccecf36c6ae6bf612174eaaac7effec854877ee/ios/chrome/app/resources/history/other_devices.js
[modify] https://crrev.com/bccecf36c6ae6bf612174eaaac7effec854877ee/third_party/WebKit/Source/core/layout/LayoutTheme.cpp
[modify] https://crrev.com/bccecf36c6ae6bf612174eaaac7effec854877ee/third_party/WebKit/Source/core/layout/LayoutThemeMac.mm
[modify] https://crrev.com/bccecf36c6ae6bf612174eaaac7effec854877ee/ui/base/l10n/l10n_util.cc
[modify] https://crrev.com/bccecf36c6ae6bf612174eaaac7effec854877ee/ui/base/l10n/l10n_util.h

bug 617540 fixed one more (in JS) with toLocaleString(). 

Archiving old bugs that haven't been modified in over two years. 

If you feel this issue should still be addressed, feel free to reopen it or to file a new issue. Thanks!