MD History: Add shortcuts for 'Delete' and 'Backspace' to delete selected items

chrome/browser/resources/md_history/app.js

Index: chrome/browser/resources/md_history/app.js
diff --git a/chrome/browser/resources/md_history/app.js b/chrome/browser/resources/md_history/app.js
index 18df6abd69253c827e6fe66b1bb9a12272d05c19..f7fc6c3b680ac1a201c8e854c985bf01048f5573 100644
--- a/chrome/browser/resources/md_history/app.js
+++ b/chrome/browser/resources/md_history/app.js
@@ -128,6 +128,9 @@ Polymer({
             !(this.$.toolbar.searchBar.showingSearch &&
               this.$.toolbar.searchBar.isSearchFocused());
         break;
+      case 'delete-command':
+        e.canExecute = this.$['history'].getHistoryList().numToBeDeleted() > 0;

[tsergeant, 2016/07/19 05:09:41]

You could probably simplify this using `this.$.toolbar.count`, which is the
number shown in the toolbar.

[lshang, 2016/07/20 01:19:09]

Done.

+        break;
     }
   },
 
@@ -138,6 +141,8 @@ Polymer({
   onCommand_: function(e) {
     if (e.command.id == 'find-command' || e.command.id == 'slash-command')
       this.$.toolbar.showSearchField();
+    if (e.command.id == 'delete-command')
+      this.deleteSelected();
   },
 
   /**