MD History: Refresh the list when clearing browsing data

chrome/browser/resources/md_history/history_list.js

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 Polymer({
   is: 'history-list',
 
   properties: {
     // The search term for the current query. Set when the query returns.
     searchedTerm: {
       type: String,
       value: '',
     },
 
     lastSearchedTerm_: String,
 
     querying: Boolean,
 
+    reloadingList_: {
+      type: Boolean,
+      value: false,
+    },
+
     // An array of history entries in reverse chronological order.
     historyData_: Array,
 
     resultLoadingDisabled_: {
       type: Boolean,
       value: false,
     },
   },
 
   listeners: {
@@ skipping 36 matching lines @@
   /**
    * Adds the newly updated history results into historyData_. Adds new fields
    * for each result.
    * @param {!Array<!HistoryEntry>} historyResults The new history results.
    */
   addNewResults: function(historyResults) {
     var results = historyResults.slice();
     /** @type {IronScrollThresholdElement} */(this.$['scroll-threshold'])
         .clearTriggers();
 
     if (this.lastSearchedTerm_ != this.searchedTerm) {

[tsergeant, 2016/08/08 05:05:12]

I'm a concerned about making the logic below more complicated, especially since
this is partly the same as the logic here for when the search term changes.

In fact, things from here like 
  this.resultLoadingDisabled_ = false;
probably need to be run when the list reloads.

Can we instead just check here whether the query is incremental or not? If it is
not an incremental query (a new search, or list reload), we should clear the
list using this block before we do anything with the new results.

list_container.js already knows whether a query was incremental, so we should be
able to pass that down to use it here.

[calamity, 2016/08/08 05:55:07]

Good idea! This code was written before the incremental vs non-incremental
change and the benefit of plumbing it here was overlooked. This is a solution
that is more semantically correct. Wew.

       this.resultLoadingDisabled_ = false;
       if (this.historyData_)
         this.splice('historyData_', 0, this.historyData_.length);
       this.fire('unselect-all');
       this.lastSearchedTerm_ = this.searchedTerm;
     }
 
     if (this.historyData_) {
-      // If we have previously received data, push the new items onto the
-      // existing array.
-      results.unshift('historyData_');
-      this.push.apply(this, results);
+      // Reload the list when browsing data is cleared.
+      if (this.reloadingList_) {
+        this.reloadingList_ = false;
+        // If we have previously received data, refresh the list unless the user
+        // has any items checked.
+        var selectedItem = this.historyData_.filter(function(item) {

[tsergeant, 2016/08/08 05:05:12]

Chris has a CL in review which makes it much easier to determine whether items
are selected, and works for both normal history and grouped history.

It should make things nicer for this patch, do you mind waiting until Chris'
patch lands?

+          return item.selected;
+        });
+        if (selectedItem.length == 0) {
+          this.splice('historyData_', 0, this.historyData_.length);
+          this.set('historyData_', results);
+        }
+      } else {
+        // Infinite scrolling. Push the new items onto the existing array.
+        results.unshift('historyData_');
+        this.push.apply(this, results);
+      }
     } else {
       // The first time we receive data, use set() to ensure the iron-list is
       // initialized correctly.
       this.set('historyData_', results);
     }
   },
 
+  reloadingList: function() {
+    this.reloadingList_ = true;
+  },
+
   /**
    * Cycle through each entry in historyData_ and set all items to be
    * unselected.
    * @param {number} overallItemCount The number of checkboxes selected.
    */
   unselectAllItems: function(overallItemCount) {
     if (this.historyData_ === undefined)
       return;
 
     for (var i = 0; i < this.historyData_.length; i++) {
@@ skipping 133 matching lines @@
     return index == 0;
   },
 
   /**
    * @private
    */
   notifyListScroll_: function() {
     this.fire('history-list-scrolled');
   },
 });