Gaia sign-in screen: Fixed CSS issues with polymer elements

Both oobe_dialog_host.css and screen_gaia_signin.css had :host rules.
Removed one from screen_gaia_signin.css
Also removed v2 class - introduced saml-interstitial class. Alternative would
be to keep saml-interstitial with the same size and not shirk it

Bug: 971172
Change-Id: Ib9e93c4bc347910286812114df29579467c0b2cf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1645360Reviewed-by: Denis Kuznetsov <antrim@chromium.org>
Commit-Queue: Roman Sorokin [CET] <rsorokin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#666248}

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

@@ -2,17 +2,11 @@
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file. */
 
-:host {
+:host(.saml-interstitial) {
   height: 528px;
   width: 448px;
 }
 
-:host(.v2) {
-  height: unset;
-  padding: unset;
-  width: unset;
-}
-
 .signin-link {
   color: rgb(37, 79, 155);
   cursor: pointer;
@@ -71,8 +65,8 @@
 }
 
 #saml-notice-recording-indicator {
-  padding-left: 10px;
-  padding-right: 10px;
+  padding-inline-end: 10px;
+  padding-inline-start: 10px;
 }
 
 #saml-notice-message {
@@ -115,11 +109,11 @@
   visibility: visible;
 }
 
-:host(.v2) #gaia-step-contents {
+:host(:not(.saml-interstitial)) #gaia-step-contents {
   display: none;
 }
 
-:host(.v2.saml) #signin-frame {
+:host(.saml) #signin-frame {
   height: 516px;
   padding-top: 44px;
 }

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

@@ -790,18 +790,15 @@ Polymer({
    * @private
    */
   updateSigninFrameContainers_: function() {
-    let oldState = this.classList.contains('v2');
-    this.classList.toggle('v2', false);
-    if (this.screenMode_ == ScreenMode.DEFAULT ||
-        this.screenMode_ == ScreenMode.OFFLINE ||
-        this.screenMode_ == ScreenMode.AD_AUTH) {
-      this.classList.toggle('v2', true);
-    }
+    const samlClass = 'saml-interstitial';
+    const containedSamlClass = this.classList.contains(samlClass);
+    this.classList.toggle(
+        samlClass, this.screenMode_ == ScreenMode.SAML_INTERSTITIAL);
     if (Oobe.getInstance().currentScreen.id != 'gaia-signin')
       return;
     // Switching between signin-frame-dialog and gaia-step-contents
     // updates screen size.
-    if (oldState != this.classList.contains('v2'))
+    if (containedSamlClass != this.classList.contains(samlClass))
       Oobe.getInstance().updateScreenSize(this);
   },