OOBE: Make adaptive OOBE square according to specs

Bug: 999090
Change-Id: I7a9e05af0f3ce2e745763551744f0a8d912356fd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1808701Reviewed-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@{#698855}

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

@@ -125,8 +125,8 @@ html:not([adaptive-oobe]) body:not(.oobe-display) #inner-container {
 html[adaptive-oobe] #oobe {
   box-sizing: border-box;
   height: 100%;
-  max-height: 736px;
-  max-width: 864px;
+  max-height: 864px; /* 768 + 48*2 */
+  max-width: 864px; /* 768 + 48*2 */
   padding-bottom: 48px;
   padding-inline-end: 48px;
   padding-inline-start: 48px;