Restore gaia-screen behavior when switching from Loading step

Bug: 981472
Change-Id: I9e73a1d482d7c796e0987b3b54c0ca606479c4bb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1932544
Commit-Queue: Denis Kuznetsov [CET] <antrim@chromium.org>
Reviewed-by: Maksim Ivanov <emaxx@chromium.org>
Reviewed-by: Roman Aleksandrov <raleksandrov@google.com>
Cr-Commit-Position: refs/heads/master@{#719171}

chrome/browser/resources/chromeos/login/screen_gaia_signin.css

@@ -97,7 +97,6 @@
   position: absolute;
   right: 0;
   top: 0;
-  visibility: hidden;
 }
 
 :host(.saml) #signin-frame-container {

chrome/browser/resources/chromeos/login/screen_gaia_signin.html

@@ -11,7 +11,7 @@
     <oobe-dialog id="signin-frame-dialog" class="gaia-dialog" role="dialog"
         has-buttons no-header no-footer-padding
         show-buttons-overlay="[[!navigationEnabled_]]"
-        hidden="[[!eq_(step_, 'online-gaia')]]">
+        hidden="[[!isStep_(step_, 'online-gaia', 'gaia-loading')]]">
       <div slot="footer" class="flex layout vertical">
         <div id="signin-frame-container"
             class$="[[getSigninFrameContainerClass_(isLoadingUiShown_)]]">
@@ -40,29 +40,29 @@
       </div>
     </oobe-dialog>
     <offline-gaia id="offline-gaia" class="gaia-dialog"
-        hidden="[[!eq_(step_, 'offline-gaia')]]">
+        hidden="[[!isStep_(step_, 'offline-gaia')]]">
     </offline-gaia>
     <offline-ad-login id="offline-ad-auth" class="gaia-dialog"
-        hidden="[[!eq_(step_, 'ad')]]"
+        hidden="[[!isStep_(step_, 'ad')]]"
         i18n-values="ad-welcome-message:loginWelcomeMessage">
     </offline-ad-login>
     <security-token-pin id="pinDialog" parameters="[[pinDialogParameters_]]"
-        hidden="[[!eq_(step_, 'pin')]]"
+        hidden="[[!isStep_(step_, 'pin')]]"
         on-cancel="onPinDialogCanceled_" on-completed="onPinDialogCompleted_">
     </security-token-pin>
     <div id="gaia-step-contents" class="step-contents"
-        hidden="[[!eq_(step_, 'saml-interstitial')]]">
+        hidden="[[!isStep_(step_, 'saml-interstitial')]]">
       <div id="gaia-signin-form-container">
         <saml-interstitial id="saml-interstitial" class="fit gaia-dialog">
         </saml-interstitial>
       </div>
     </div>
     <div id="gaia-loading" class="step-loading gaia-dialog"
-        hidden="[[!eq_(step_, 'loading')]]">
+        hidden="[[!isStep_(step_, 'loading', 'gaia-loading')]]">
       <throbber-notice i18n-values="text:gaiaLoading"></throbber-notice>
     </div>
     <notification-card id="gaia-whitelist-error" type="fail" class="gaia-dialog"
-        hidden="[[!eq_(step_, 'whitelist-error')]]"
+        hidden="[[!isStep_(step_, 'whitelist-error')]]"
         i18n-values="button-label:tryAgainButton;
                      link-label:learnMoreButton">
     </notification-card>

chrome/browser/resources/chromeos/login/screen_gaia_signin.js

@@ -60,6 +60,7 @@ const DialogMode = {
   GAIA: 'online-gaia',
   OFFLINE_GAIA: 'offline-gaia',
   OFFLINE_AD: 'ad',
+  GAIA_LOADING: 'gaia-loading',
   LOADING: 'loading',
   PIN_DIALOG: 'pin',
   GAIA_WHITELIST_ERROR: 'whitelist-error',
@@ -94,6 +95,7 @@ Polymer({
 
     /**
      * Current step displayed.
+     * @type {DialogMode}
      * @private
      */
     step_: {
@@ -1591,10 +1593,15 @@ Polymer({
   },
 
   /**
-   * Simple equality comparison function.
+   * Checks if current step is one of specified steps.
+   * @param {DialogMode} currentStep Name of current step.
+   * @param {...string} stepsVarArgs List of steps to compare with.
+   * @return {boolean}
    */
-  eq_: function(currentStep, expectedStep) {
-    return currentStep == expectedStep;
+  isStep_: function(currentStep, ...stepsVarArgs) {
+    if (stepsVarArgs.length < 1)
+      throw Error('At least one step to compare is required.');
+    return stepsVarArgs.some(step => currentStep === step);
   },
 
   /**
@@ -1610,7 +1617,11 @@ Polymer({
       return;
     }
     if (isLoading) {
+      if (mode == AuthMode.DEFAULT) {
+        this.step_ = DialogMode.GAIA_LOADING;
+      } else {
         this.step_ = DialogMode.LOADING;
+      }
       return;
     }
     if (isWhitelistError) {