Fix Google logo on NTP in Forced-colors mode

Background images are normally hidden in forced-colors mode,
but the Google logo should still be visible. It'd be worth
considering making it an <img> instead, but in the meantime,
forced-color-adjust: none is a simpler, safer, targeted fix.

Bug: 1166383
Change-Id: Ie29b351020c652a6fe381bcdce6ef4a9a1e03d66
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2627966
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Tibor Goldschwendt <tiborg@chromium.org>
Reviewed-by: Tibor Goldschwendt <tiborg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#843325}

chrome/browser/resources/new_tab_page/logo.html

@@ -13,6 +13,7 @@
   }
 
   #logo {
+    forced-color-adjust: none;
     height: 92px;
     width: 272px;
   }