[CrOS Cellular] Select invalid PIN inputs.

A previous CL [1] ensured that valid but incorrect inputs were selected
after a failed attempt. However, this fix missed an edge case of inputs
which are invalid (e.g., PINs which contain letters instead of digits).

This CL causes these invalid values to be selected when they fail
validation.

[1] https://chromium-review.googlesource.com/c/chromium/src/+/1733421

Bug: 986793
Change-Id: Ib0d94219ebdd59af49f9b3cf35c3cbb92f27ada1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1790094
Auto-Submit: Kyle Horimoto <khorimoto@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#694468}

ui/webui/resources/cr_components/chromeos/network/network_siminfo.js

@@ -525,7 +525,8 @@ Polymer({
   /**
    * Checks whether |pin1| is of the proper length and contains only digits.
    * If opt_pin2 is not undefined, then it also checks whether pin1 and
-   * opt_pin2 match. On any failure, sets |this.error_| and returns false.
+   * opt_pin2 match. On any failure, sets |this.error_|, focuses the invalid
+   * PIN, and returns false.
    * @param {string} pin1
    * @param {string=} opt_pin2
    * @return {boolean} True if the pins match and are of minimum length.
@@ -537,10 +538,12 @@ Polymer({
     }
     if (pin1.length < PIN_MIN_LENGTH || !DIGITS_ONLY_REGEX.test(pin1)) {
       this.error_ = ErrorType.INVALID_PIN;
+      this.focusDialogInput_();
       return false;
     }
     if (opt_pin2 != undefined && pin1 != opt_pin2) {
       this.error_ = ErrorType.MISMATCHED_PIN;
+      this.focusDialogInput_();
       return false;
     }
     return true;