MD Downloads: limit the amount of downloads we send

chrome/browser/resources/md_downloads/manager.js

Index: chrome/browser/resources/md_downloads/manager.js
diff --git a/chrome/browser/resources/md_downloads/manager.js b/chrome/browser/resources/md_downloads/manager.js
index 91faf6a1b79d08f3c5aac0e36f91656190a8bf12..cd57fad4fb61d303bad0ebee0bc1585329f469ce 100644
--- a/chrome/browser/resources/md_downloads/manager.js
+++ b/chrome/browser/resources/md_downloads/manager.js
@@ -22,6 +22,10 @@ cr.define('downloads', function() {
       loading: true,
     },
 
+    listeners: {
+      'downloads-list.scroll': 'onListScroll_',
+    },
+
     observers: [
       'itemsChanged_(items_.*)',
     ],
@@ -89,14 +93,26 @@ cr.define('downloads', function() {
         downloads.ActionService.getInstance().undo();
     },
 
+    /**
+     * @param {Event} e
+     * @private
+     */
+    onListScroll_: function(e) {
+      var list = this.$['downloads-list'];
+      if (list.scrollHeight > list.offsetHeight &&

[asanka, 2015/12/07 20:31:50]

Imma n00b. Shouldn't this be list.scrollHeight > list.clientHeight ?

[Dan Beam, 2015/12/09 06:55:21]

https://drafts.csswg.org/cssom-view/#dom-htmlelement-offsetheight
https://drafts.csswg.org/cssom-view/#dom-element-clientheight

there is no border nor horizontal scrollbar on the list in this case, so these
are equivalent, but I think `offsetHeight` is actually the correcter thing to
use here.

+          list.scrollTop + list.offsetHeight == list.scrollHeight) {
+        // Reached the end of the scrollback. Attempt to load more items.
+        downloads.ActionService.getInstance().loadMore();
+      }
+    },
+
     /** @private */
     onLoad_: function() {
       cr.ui.decorate('command', cr.ui.Command);
       document.addEventListener('canExecute', this.onCanExecute_.bind(this));
       document.addEventListener('command', this.onCommand_.bind(this));
 
-      // Shows all downloads.
-      downloads.ActionService.getInstance().search('');
+      downloads.ActionService.getInstance().loadMore();
     },
 
     /**