Yingbing, can you please take a look? Is the LM for Chinese Pinyin dynamically downloaded?

1. Pinyin language model is built in package. So pinyin IME can be activated on boot.
2. Not repro in ChromeOS.

The bug description "Display chromium OS in this language".
Does that mean it's a chromiumOS not chromeOS

Thanks for the clarification. This is for ChromiumOS build from ToT. I tried this  on Chromium similator gn args. 

is_component_build = true
is_debug = false
use_goma = true
is_asan = false
dcheck_always_on = true
target_os = "chromeos"
use_ozone = true
ozone_auto_platforms = false
ozone_platform_x11 = true
enable_nacl=true

Can you retry on ChromiumOS? Thanks!

The ChromiumOS is open sourced, and the official IME extension is closed sourced.
Therefore, we have a separated IME extension for ChromiumOS.
That means ChromiumOS cannot work with close sourced IME extension.

Please set:
is_official_build = true
is_chrome_branded = true

Thanks Shu Chen. I still couldn't see the candidate list pop up with ChromeOS official build (with src-internal repo). I selected "Display Chrome OS in this language" this time now. 

How do you start Chrome with pinyin IME activated on boot? I have to change the input method after Chrome starts which may be the bug here.

My updated gn args list:

is_official_build = true
is_chrome_branded = true
is_debug = false
use_goma = true
is_asan = false
dcheck_always_on = true
target_os = "chromeos"
use_ozone = true
ozone_auto_platforms = false
ozone_platform_x11 = true
enable_nacl=true

Are you using a real chrome os device to test? Or using linux_chromeos on a workstation machine?

Thanks Shuchen. I just tried on a real chrome os device and the candidate pop up list works, yay. However, candidate pop-up list doesn't appear using linux_chromeos on a workstation Goobuntu machine. I'm not sure if this is a known bug or expected behaviour.

You mention above that there's a separated IME extension for ChromiumOS. Do you have instructions on how I can grab this, maybe this extension will make the popup list work? Do you folks use Chrome simulator during IME development or just use chrome os device? Thank you!

The IME extension is not bundled in the chromium/chrome binary.
It is a separated package located at /usr/share/chromeos-assets/input_method/input_tools/.

If you want to test IME on linux_chromeos, please copy the package content files to /usr/share/chromeos-assets/input_method/input_tools/ on your linux box.

Thanks for the following-up conversation Shu Chen and the link
https://cs.chromium.org/chromium/src/chrome/browser/resources/chromeos/input_method/google_xkb_manifest.json?l=40

I renamed the above folder input_method to input_methods and candidate pop-up list is displayed just fine.