WebUI Tab Strip: Update shadow on drag image

https://i.imgur.com/iep45bz.png

Fixed: 1035675
Change-Id: Ic73a425a68b5e7275df29f347592715880d39259
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2106348Reviewed-by: Esmael Elmoslimany <aee@chromium.org>
Commit-Queue: John Lee <johntlee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#751079}

chrome/browser/resources/tab_strip/tab_list.html

@@ -5,8 +5,8 @@
     --tabstrip-tab-width: var(--tabstrip-tab-thumbnail-width);
     --tabstrip-tab-spacing: 16px;
     --tabstrip-tab-dragging-shadow:
-        0 4px 4px 0 rgba(var(--google-grey-800-rgb), .3),
-        0 8px 12px 6px rgba(var(--google-grey-800-rgb), .15);
+        0 2px 3px 0 rgba(var(--google-grey-800-rgb), .3),
+        0 6px 10px 4px rgba(var(--google-grey-800-rgb), .15);
 
 <if expr="not chromeos">
     --tabstrip-tab-drag-image-scale: 1.1;