ime: Record KOREAN category for Korean input method.

Korean used to be supported as a separate extension, where the IDs started with "hangul_".
However, in [1], we added first-party support for Korean on Google branded builds, but the ID
is "ko-t-i0-und".

Currently "ko-t-i0-und" is recorded as T13N for metrics. Add an additional branch in the metrics
code so that "ko-t-i0-und" is recorded as Korean too.

[1] https://codereview.chromium.org/2898873002/diff/1/chrome/browser/resources/chromeos/input_method/google_xkb_manifest.json

Change-Id: If6c6c1af12d0ae7715a561fecbb803a7940575d9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2497630Reviewed-by: David Vallet <dvallet@chromium.org>
Commit-Queue: Darren Shen <shend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#821566}

chrome/browser/chromeos/input_method/input_method_manager_impl.cc

@@ -90,7 +90,8 @@ InputMethodCategory GetInputMethodCategory(const std::string& input_method_id) {
                               base::CompareCase::SENSITIVE)) {
     category = INPUT_METHOD_CATEGORY_JA;
   } else if (base::StartsWith(component_id, "hangul_",
-                              base::CompareCase::SENSITIVE)) {
+                              base::CompareCase::SENSITIVE) ||
+             component_id == "ko-t-i0-und") {
     category = INPUT_METHOD_CATEGORY_KO;
   } else if (base::StartsWith(component_id, "vkd_",
                               base::CompareCase::SENSITIVE)) {