[NTP] Scroll to top when opening the richer picker

Bug: 937570
Change-Id: I03a33767498591dbe4c72594253766227659c809
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1700175
Commit-Queue: Kyle Milka <kmilka@chromium.org>
Auto-Submit: Kyle Milka <kmilka@chromium.org>
Reviewed-by: Gayane Petrosyan <gayane@chromium.org>
Cr-Commit-Position: refs/heads/master@{#677114}

chrome/browser/resources/local_ntp/customize.js

@@ -1343,6 +1343,7 @@ customize.richerPicker_resetCustomizationMenu = function() {
  * Close and reset the customization menu.
  */
 customize.richerPicker_closeCustomizationMenu = function() {
+  $(customize.IDS.BACKGROUNDS_MENU).scrollTop = 0;
   $(customize.IDS.CUSTOMIZATION_MENU).close();
   customize.richerPicker_resetCustomizationMenu();