MD History: Implement search functionality.

chrome/browser/resources/md_history/history_item.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-item',
   properties: {
     timeAccessed: {
       type: String,
       value: ''
     },
 
     websiteTitle: {
       type: String,
-      value: ''
+      value: '',
+      observer: 'setSearchedTextToBold_'
     },
 
     // Domain is the website text shown on the history-item next to the title.
     // Gives the user some idea of which history items are different pages
     // belonging to the same site, and can be used to look for more items
     // from the same site.
     websiteDomain: {
       type: String,
       value: ''
     },
@@ skipping 13 matching lines @@
       value: false,
       reflectToAttribute: true
     },
 
     // The time in seconds of when the website was accessed.
     timestamp: {
       type: Number,
       value: 0
     },
 
+    // Search term used in the chrome.send to obtain this history-item.
+    searchTerm: {
+      type: String,
+      value: '',
+      observer: 'setSearchedTextToBold_'
+    },
+
     selected: {
       type: Boolean,
       value: false,
       notify: true
     }
   },
 
   /**
    * When a history-item is selected the toolbar is notified and increases
    * or decreases its count of selected items accordingly.
@@ skipping 23 matching lines @@
   openMenu: function(e) {
     var position = this.$['menu-button'].getBoundingClientRect();
 
     this.fire('toggle-menu', {
       x: position.left,
       y: position.top,
       accessTime: this.timestamp
     });
     // Stops the 'tap' event from closing the menu when it opens.
     e.stopPropagation();
+  },
+
+  /**
+   * If the results shown are search results set the search term to be bold
+   * where it is displayed in the history-item title.
+   * @private
+   */
+  setSearchedTextToBold_: function() {

[tsergeant, 2016/02/02 02:57:36]

This is generally good. The thing that's a little messy is that you're changing
the contents of a node which is meant to be managed by Polymer.

I would get rid of the {{websiteTitle}} from this line in history_item.html:
<a href="{{websiteUrl_}}" id="title">{{websiteTitle_}}</a>

To make sure that this function is the only one responsible for the contents of
that node.

[hsampson, 2016/02/03 02:37:59]

Done.

+    var i = 0;
+    if ((this.searchTerm != '') && (this.searchTerm != null)) {
+      var searchText = new RegExp(this.quoteString_(this.searchTerm), 'gim');
+      var match;
+      this.$['title'].textContent = '';

[tsergeant, 2016/02/02 02:57:36]

Just use this.$.title

[hsampson, 2016/02/03 02:37:59]

Done.

+      while (match = searchText.exec(this.websiteTitle)) {
+        if (match.index > i)
+          this.$['title'].appendChild(document.createTextNode(
+                this.websiteTitle.slice(i, match.index)));
+        i = searchText.lastIndex;
+        // Mark the highlighted text in bold.
+        var b = document.createElement('b');
+        b.textContent = this.websiteTitle.substring(match.index, i);
+        this.$['title'].appendChild(b);
+      }
+      if (i < this.websiteTitle.length)
+        this.$['title'].appendChild(document.createTextNode(
+                this.websiteTitle.slice(i)));
+    } else {
+      this.$['title'].textContent = this.websiteTitle;
+    }
+  },
+
+  /**
+   * Quote a string so it can be used in a regular expression.
+   * @param {string} str The source string.
+   * @return {string} The escaped string.
+   * @private
+   */
+  quoteString_: function(searchTerm) {
+    return searchTerm.replace(/([\\\.\+\*\?\[\^\]\$\(\)\{\}\=\!\<\>\|\:])/g,
+        '\\$1');
   }
 });