MD Settings: Use scrollable behavior for all iron-list containers

chrome/browser/resources/settings/search_engines_page/search_engines_list.js

Index: chrome/browser/resources/settings/search_engines_page/search_engines_list.js
diff --git a/chrome/browser/resources/settings/search_engines_page/search_engines_list.js b/chrome/browser/resources/settings/search_engines_page/search_engines_list.js
index 391444486e1141af676e25bc86117cd0f7872237..d196acaa7856bdb7d0720f01ed1743f7dd00e7fd 100644
--- a/chrome/browser/resources/settings/search_engines_page/search_engines_list.js
+++ b/chrome/browser/resources/settings/search_engines_page/search_engines_list.js
@@ -9,6 +9,8 @@
 Polymer({
   is: 'settings-search-engines-list',
 
+  behaviors: [CrScrollableBehavior],
+
   properties: {
     /** @type {!Array<!SearchEngine>} */
     engines: {
@@ -20,8 +22,6 @@ Polymer({
 
   /** @private */
   enginesChanged_: function() {
-    // Rather than adding an event to notify this element when it is shown,
-    // observe changes to |engines| and notify the iron-list.
-    this.$$('iron-list').fire('iron-resize');
+      this.updateScrollableContents();

[dpapad, 2016/09/17 00:05:53]

I am not familiar with CrScrollableBehavior. By reading the documentation,
sounds useful (consistent styling, keyboard behavior), but it also seems it is
forcing the use of iron-list.

iron-list (per its own documentation) is useful for "infinite" lists. I think it
might be too big of a hammer to apply everywhere, instead of the simpler chunked
dom-repeat. The contents of updateScrollableContens() involves setInterval and I
have to admit that it scares me.

So my question is whether using iron-list for search engines is the best path
forward, and in general for any list that in the 90th percentile has at most 100
entries (those numbers are per my expectation, we can probably get actual
numbers on this). Same question holds for the "startup URLs". Do we really need
an infinite list for those?

[stevenjb, 2016/09/19 16:19:15]

We switched to iron-list primarily for its keyboard navigation behavior which is
fairly subtle and complex and not encapsulated into a separate behavior. I did
play with other options with the existing dom-repeat but did not have much
success with getting the behavior we desire.

We can discuss this more at today's standup.

   },
 });