[NTP] Explicitly set ntp-contents height for non-google-page.

If this is not set, the #ntp-contents height is inherited, which applies
from the "top" location specified in .non-google-page, but using the
size of the overall NTP content area (at 100%), resulting in an
unnecessary scrollbar. The chosen height corresponds to MV tile height
for a single row, but also works for a row of icons, and works well on
small screens (like Pixelbook), as well as high-res screens.

Bug: 855834

Cq-Include-Trybots: luci.chromium.try:closure_compilation
Change-Id: I8b342e066c8ddcb51b51e9f03a85e9181a001020
Reviewed-on: https://chromium-review.googlesource.com/1136860
Commit-Queue: Ramya Nagarajan <ramyan@chromium.org>
Reviewed-by: Mathieu Perreault <mathp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575053}

chrome/browser/resources/local_ntp/local_ntp.css

@@ -98,6 +98,12 @@ button {
 }
 
 .non-google-page #ntp-contents {
+  /* The inherited height from #ntp-contents applies from the "top" location,
+   * but uses the size of the overall NTP content area, resulting in an
+   * unnecessary scrollbar. This height corresponds to MV tile height for a
+   * single row, but also works for a row of icons, and works well on small
+   * screens (like Pixelbook), as well as high-res screens. */
+  height: 155px;
   left: calc(50% - var(--content-width)/2);
   position: absolute;
   top: calc(50% - 155px);