OOBE: Set min-height for OOBE screens

Also remove shelf-padding when virtual keyboard is shown

Bug: 1011757, 1006797
Change-Id: I4d6a2adab2889796062898bd9f93c466f930138d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1847335Reviewed-by: Roman Sorokin [CET] <rsorokin@chromium.org>
Reviewed-by: Denis Kuznetsov <antrim@chromium.org>
Commit-Queue: Roman Sorokin [CET] <rsorokin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#704150}

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

@@ -114,6 +114,7 @@ html:not([full-screen-dialog]) #oobe.tpm-error-message #inner-container {
   height: 100%;
   max-height: 864px; /* 768 + 48*2 */
   max-width: 864px; /* 768 + 48*2 */
+  min-height: 560px; /* 464 + 48*2 */
   padding-bottom: 48px;
   padding-inline-end: 48px;
   padding-inline-start: 48px;

ui/login/display_manager.js

@@ -200,7 +200,16 @@ cr.define('cr.ui.login', function() {
      * Whether the virtual keyboard is displayed.
      * @type {boolean}
      */
-    virtualKeyboardShown: false,
+    virtualKeyboardShown_: false,
+
+    get virtualKeyboardShown() {
+      return this.virtualKeyboardShown_;
+    },
+
+    set virtualKeyboardShown(shown) {
+      this.virtualKeyboardShown_ = shown;
+      document.documentElement.setAttribute('virtual-keyboard', shown);
+    },
 
     /**
      * Type of UI.

ui/login/oobe.css

@@ -21,6 +21,7 @@ html {
   --shelf-area-height: var(--shelf-area-height-base);
 }
 
+html[virtual-keyboard=true],
 html[screen=gaia-signin] {
   --shelf-area-height: 0;
 }