MD History: Delete button in the toolbar allows deletion of multiple history-items.

chrome/browser/resources/md_history/history-card-manager.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-card-manager',
 
   properties: {
     // An array of objects sorted in reverse chronological order.
     // Each object has a date and the history items belonging to that date.
@@ skipping 87 matching lines @@
     }
     this.appendHistoryData_(currentDate, historyItems);
 
     this.lastVisitedTime = historyItems[historyItems.length - 1].time;
     this.$['infinite-list'].scrollTop = scrollPosition;
   },
 
   /**
    * Cycle through each entry in historyDataByDay_ and set all items to be
    * unselected.
+   * @param {number} overallItemCount the number of items selected.
    */
   unselectAllItems: function(overallItemCount) {
     var historyCardData = this.historyDataByDay_;
 
     for (var i = 0; i < historyCardData.length; i++) {
       var items = historyCardData[i].historyItems;
       for (var j = 0; j < items.length; j++) {
         if (items[j].selected) {
           this.set('historyDataByDay_.' + i + '.historyItems.' + j +
               '.selected', false);
           overallItemCount--;
           if (overallItemCount == 0) {
             break;
           }
         }
       }
     }
   },
 
   /**
+   * Remove all selected items from the overall array so that they are also
+   * removed from view. Make sure that the card length and positioning is
+   * updated accordingly.
+   * @param {number} overallItemCount the number of items selected.
+   */
+  removeDeletedHistory: function(overallItemCount) {
+    var itemDeletedFromCard = false;
+
+    for (var i = 0; i < this.historyDataByDay_.length; i++) {
+      var items = this.historyDataByDay_[i].historyItems;
+
+      for (var j = items.length - 1; j > -1; j--) {
+        if (items[j].selected) {
+          this.splice('historyDataByDay_.' + i + '.historyItems', j, 1);
+          itemDeletedFromCard = true;

[tsergeant, 2016/01/18 02:33:52]

There's a subtle issue here:

itemDeletedFromCard will be set to true after a single item is deleted, and then
will remain true for every other card. You'll need to make sure you reset it
after every card.

[hsampson, 2016/01/19 23:41:39]

Done.

+          overallItemCount--;
+          if (overallItemCount == 0)
+            break;
+        }
+      }
+      if (itemDeletedFromCard) {

[tsergeant, 2016/01/18 02:33:52]

Nit: Remove {}

[hsampson, 2016/01/19 23:41:39]

Done.

+        this.$['infinite-list'].updateSizeForItem(i);
+      }
+      if (overallItemCount == 0)

[tsergeant, 2016/01/18 02:33:52]

Why is overallItemCount checked twice? Is it sufficient to just check it in the
inner for loop?

[hsampson, 2016/01/19 23:41:39]

Done.

+        break;
+    }
+    this.removeExtraCards_();
+  },
+
+  /**
+   * If a given day has had all the history it contains removed, remove this
+   * day from the array.
+   * @private
+   */
+  removeExtraCards_: function() {

[tsergeant, 2016/01/18 02:33:52]

Nit: Rename to removeEmptyCards?

[hsampson, 2016/01/19 23:41:39]

Done.

+    var historyCards = this.historyDataByDay_;
+    for (var i = historyCards.length - 1; i > -1; i--) {
+      if (historyCards[i].historyItems.length == 0) {
+        this.splice('historyDataByDay_', i, 1);
+      }
+    }
+  },
+
+  /**
    * Adds the given items into historyDataByDay_. Adds items to the last
    * existing day if the date matches, creates a new element otherwise.
    * @param {string} date The date of the history items.
    * @param {array} historyItems The list of history items for the current date.
    * @private
    */
   appendHistoryData_: function(date, historyItems) {
     var lastIndex = this.historyDataByDay_.length - 1;
     if (lastIndex > 0 && date == this.historyDataByDay_[lastIndex].date) {
       // A new object is required for the card to update due to iron-list's
       // pass by reference implementation.
       var items = this.historyDataByDay_[lastIndex]
                       .historyItems.concat(historyItems);
       this.splice('historyDataByDay_', lastIndex, 1, {
         date: date,
         historyItems: items,
       });
     } else {
       this.push('historyDataByDay_', {
         date: date,
         historyItems: historyItems
       });
     }
   },
 
   /**
+   * Based on which items are selected, collect an array of the info required
+   * for chrome.send('removeHistory', ...).
+   * @param {number} count The number of items that are selected.
+   * @return {array} toBeRemoved An array of objects which contain information
+   * on which history-items should be deleted.
+   */
+  listOfItemsToDelete: function(count) {

[tsergeant, 2016/01/18 02:33:52]

Nit: rename to getItemsToDelete

[hsampson, 2016/01/19 23:41:39]

Done.

+    var toBeRemoved = [];
+    for (var i = 0; i < this.historyDataByDay_.length; i++) {
+      var items = this.historyDataByDay_[i].historyItems;
+      for (j = 0; j < items.length; j++) {
+        if (items[j].selected) {
+
+          toBeRemoved.push({
+            url: items[j].url,
+            timestamps: items[j].allTimestamps
+          });
+
+          count--;
+          if (count == 0) {

[tsergeant, 2016/01/18 02:33:52]

Nit: Remove {}

[hsampson, 2016/01/19 23:41:39]

Done.

+            break;
+          }
+        }
+      }
+    }
+    return toBeRemoved;
+  },
+
+  /**
    * Called when the card manager is scrolled.
    */
   scrollHandler: function(e) {
     // Closes overflow menu on scroll.
     this.closeMenu();
 
     this.doInfiniteScroll_(e);
   },
 
   /**
    * Requests the next list of results when the scrollbar is near the bottom
    * of the window.
    */
   doInfiniteScroll_: function(e) {
     var scrollOffset = 10;
     var scrollElem = e.srcElement;
 
     if (scrollElem.scrollHeight <=
         scrollElem.scrollTop + scrollElem.clientHeight + scrollOffset) {
       chrome.send('queryHistory',
           ['', 0, 0, this.lastVisitedTime, RESULTS_PER_PAGE]);
     }
   }
 });