Add full-screen-dialog property for all OOBE-resumable screens

Bug: 1018105, 1014859
Change-Id: I293216a4dfe9f6d56bae7a1dd09f73d74025f72e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1948840Reviewed-by: Roman Aleksandrov <raleksandrov@google.com>
Commit-Queue: Denis Kuznetsov [CET] <antrim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#721121}

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

@@ -14,7 +14,7 @@
     <link rel="stylesheet" href="oobe_flex_layout.css">
     <oobe-dialog id="eulaLoadingDialog" hidden="[[!eulaLoadingScreenShown]]"
         role="dialog" i18n-values="aria-label:termsOfServiceLoading"
-        has-buttons>
+        has-buttons full-screen-dialog>
       <iron-icon icon="oobe-eula:googleg" slot="oobe-icon"></iron-icon>
       <h1 slot="title">[[i18nDynamic(locale, 'termsOfServiceLoading')]]</h1>
     </oobe-dialog>

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

@@ -8,7 +8,7 @@
     <link rel="stylesheet" href="oobe_flex_layout.css">
     <oobe-dialog id="networkDialog" role="dialog" on-show-dialog="onShown_"
         aria-label$="[[i18nDynamic(locale, 'networkSectionTitle')]]"
-        has-buttons>
+        has-buttons full-screen-dialog>
       <hd-iron-icon slot="oobe-icon"
           icon1x="oobe-network-32:dialog-icon-wifi"
           icon2x="oobe-network-64:dialog-icon-wifi">

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

@@ -28,7 +28,8 @@
     <link rel="stylesheet" href="oobe_flex_layout.css">
     <link rel="stylesheet" href="oobe_update.css">
     <oobe-dialog hidden="[[!checkingForUpdate]]" tabindex="0"
-        aria-live="polite" id="checking-for-updates-dialog" footer-shrinkable>
+        aria-live="polite" id="checking-for-updates-dialog" footer-shrinkable
+        full-screen-dialog>
       <iron-icon icon="oobe-update:googleg" slot="oobe-icon"></iron-icon>
       <h1 slot="title" i18n-content="checkingForUpdates"></h1>
       <div slot="subtitle" class="update-subtitle" id="checkingForUpdatesMsg"