Fix NTP background picker when the browser is very narrow

When the browser is resized to be very, very narrow the picker should
resize to one column. At this point the option dialog will also need
to be resized and the text may now overflow.

Bug: 850338
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I06d08f15b631f9810ead7e01180aacf2a4a66c18
Reviewed-on: https://chromium-review.googlesource.com/1097461Reviewed-by: Mathieu Perreault <mathp@chromium.org>
Commit-Queue: Kyle Milka <kmilka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#566711}

chrome/browser/resources/local_ntp/custom_backgrounds.css

@@ -84,9 +84,12 @@
 .bg-option-text {
   display: inline-block;
   line-height: normal;
+  overflow: hidden;
   padding-left: 16px;
   text-align: center;
+  text-overflow: ellipsis;
   vertical-align: middle;
+  white-space: nowrap;
 }
 
 #bg-sel-menu-overlay {
@@ -122,6 +125,13 @@
    }
 }
 
+@media (max-width: 356px) {
+   #bg-sel-menu,
+   #edit-bg-dialog {
+     width: 188px;
+   }
+}
+
 #bg-sel-tiles {
   height: 284px;
   overflow-y: scroll;