Make table in chrome:site-engagement sortable.

chrome/browser/resources/engagement/engagement_table.css

Index: chrome/browser/resources/engagement/engagement_table.css
diff --git a/chrome/browser/resources/engagement/engagement_table.css b/chrome/browser/resources/engagement/engagement_table.css
index 55318c35756a125e626b57a676623634837f0a42..937ba80f3415966d3ea4f95fd1abf490c50b0669 100644
--- a/chrome/browser/resources/engagement/engagement_table.css
+++ b/chrome/browser/resources/engagement/engagement_table.css
@@ -13,8 +13,24 @@ table th {
 
 table th {
   background: rgb(224, 236, 255);
+  cursor: pointer;
+  padding-bottom: 4px;
+  padding-top: 4px;
+  white-space: nowrap;
 }
 
 .origin-cell {
   min-width: 500px;
 }
+
+table tr:hover {
+  background: rgb(255, 255, 187);
+}
+
+.sort-column::after {
+  content: '\25B2';

[Dan Beam, 2015/10/29 00:50:00]

any reason not to use '▲' directly?

[calamity, 2015/10/29 02:46:01]

Done.

+}
+
+:host([sort-reverse_]) .sort-column::after {

[Dan Beam, 2015/10/29 00:50:00]

nit: don't use _ in this case, IMO

[calamity, 2015/10/29 02:46:01]

Done.

+  content: '\25BC';

[Dan Beam, 2015/10/29 00:50:00]

same nit, re: ▼

[calamity, 2015/10/29 02:46:01]

Done.

+}