downloads: break downloads.js into more classes/files.

chrome/browser/resources/downloads/downloads.js

Index: chrome/browser/resources/downloads/downloads.js
diff --git a/chrome/browser/resources/downloads/downloads.js b/chrome/browser/resources/downloads/downloads.js
index 0a074b7bf28f290c4615c3195488864ef9ee92f1..c8697755222bf7da57c62c2d3c43e3c293799157 100644
--- a/chrome/browser/resources/downloads/downloads.js
+++ b/chrome/browser/resources/downloads/downloads.js
@@ -172,10 +172,6 @@ function Downloads() {
   this.searchText_ = '';
   this.focusGrid_ = new cr.ui.FocusGrid();
 
-  // Keep track of the dates of the newest and oldest downloads so that we
-  // know where to insert them.
-  this.newestTime_ = -1;
-
   // Icon load request queue.
   this.iconLoadQueue_ = [];
   this.isIconLoading_ = false;
@@ -202,17 +198,21 @@ Downloads.prototype.updated = function(download) {
     this.downloads_[id].update(download);
   } else {
     this.downloads_[id] = new Download(download);
-    // We get downloads in display order, so we don't have to worry about
-    // maintaining correct order - we can assume that any downloads not in
-    // display order are new ones and so we can add them to the top of the
-    // list.
-    if (download.started > this.newestTime_) {
-      this.node_.insertBefore(this.downloads_[id].node, this.node_.firstChild);
-      this.newestTime_ = download.started;
-    } else {
-      this.node_.appendChild(this.downloads_[id].node);
+
+    // Sort downloads by start time and insert the new one in the right place.
+    var startSorted = [];
+    for (var sortedId in this.downloads_) {
+      startSorted.push(this.downloads_[sortedId]);
     }
+    startSorted.sort(function(d1, d2) { return d2.started_ - d1.started_; });
+
+    var indexOfNewDownload = startSorted.indexOf(this.downloads_[id]);
+    var before = startSorted[indexOfNewDownload + 1];
+
+    // If !before, insertBefore() acts like appendChild() and adds at the end.
+    this.node_.insertBefore(this.downloads_[id].node, before && before.node);

[Dan Beam, 2015/03/03 19:31:05]

i could possibly do this:

  if (startSorted.length > MAX_DOWNLOADS)
    this.remove(startSorted.pop().id_);

but it's not crazy efficient in the Clear All + undo case

[asanka, 2015/03/03 20:45:56]

Yeah. For undo operations that affect multiple downloads, we'd probably be
better off sending the whole list. I've suggested that we do so for single
downloads as well and be done with it. If that's too excessive, then maybe we
can consider something like this for the single download case.

[Dan Beam, 2015/03/04 00:46:20]

the problem with rebuilding DOM is that it messes up focus.  we recently fixed
this on chrome://extensions and it'd be a pretty huge bummer to regress it here.

   }
+
   // Download.prototype.update may change its nodeSince_ and nodeDate_, so
   // update all the date displays.
   // TODO(benjhayden) Only do this if its nodeSince_ or nodeDate_ actually did
@@ -373,10 +373,7 @@ Downloads.prototype.scheduleIconLoad = function(elem, iconURL) {
  * @return {boolean} Returns true if the displayed list is to be updated.
  */
 Downloads.prototype.isUpdateNeeded = function(downloads) {
-  var size = 0;
-  for (var i in this.downloads_)
-    size++;
-  if (size != downloads.length)
+  if (this.size() != downloads.length)
     return true;
   // Since there are the same number of items in the incoming list as
   // |this.downloads_|, there won't be any removed downloads without some
@@ -633,6 +630,7 @@ Download.prototype.update = function(download) {
   this.fileUrl_ = download.file_url;
   this.fileName_ = download.file_name;
   this.url_ = download.url;
+  this.started_ = download.started;
   this.state_ = download.state;
   this.fileExternallyRemoved_ = download.file_externally_removed;
   this.dangerType_ = download.danger_type;