[chrome:omnibox] Reduce table header and body row heights.

Reduced table body row heights from 44px to 42px. 42px is just sufficient to
display 3 lines. Any less, and cells with 3 lines of contents would grow in
height on hover. 3 lines seems sufficient for most matches without consuming too
much vertical space.

Reduced table header row padding from 20 (top) and 10px (bottom) to 12 and 6px
respectively. This looks more visually pleasing and consumes less vertical space
without appearing cramped compared with the adjacent table rows.

Bug: 891303
Change-Id: I75efba70799163bd7f33e1340cfecdd2d1bb45a3
Reviewed-on: https://chromium-review.googlesource.com/c/1374400Reviewed-by: Tommy Li <tommycli@chromium.org>
Commit-Queue: manuk hovanesian <manukh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#616018}

chrome/browser/resources/omnibox/omnibox.css

@@ -75,7 +75,7 @@ thead tr {
 }
 
 tbody tr {
-  height: 44px;
+  height: 42px;
   transition-duration: 300ms;
 }
 
@@ -90,8 +90,8 @@ td {
 }
 
 th {
-  padding-bottom: 10px;
-  padding-top: 20px;
+  padding-bottom: 6px;
+  padding-top: 12px;
 }
 
 .filtered-highlighted {