MD Settings: Proof of concept, highlighting search matches across Shadow DOM boundaries.

chrome/browser/resources/settings/search_settings.js

Index: chrome/browser/resources/settings/search_settings.js
diff --git a/chrome/browser/resources/settings/search_settings.js b/chrome/browser/resources/settings/search_settings.js
new file mode 100644
index 0000000000000000000000000000000000000000..3a25d0e814524420329eaf28b3196d11bb3f5357
--- /dev/null
+++ b/chrome/browser/resources/settings/search_settings.js
@@ -0,0 +1,139 @@
+// Copyright 2016 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.
+
+(function() {
+  var WRAPPER_CSS_CLASS = 'search-highlight-wrapper';
+  var HIT_CSS_CLASS = 'search-highlight-hit';
+
+  function findChildren_(element) {
+    var children = [];
+    var walker = document.createTreeWalker(
+        element.shadowRoot, NodeFilter.SHOW_ELEMENTS, null, false);
+    var node = walker.nextNode();
+    while (node) {
+      if (!!node.shadowRoot)
+        children.push(node);
+
+      node = walker.nextNode();
+    }
+    return children;
+  }
+
+  /**
+   * Highlights all matches in the given element. Ignores children that have
+   * their own Shadow DOW.
+   * @param {!RegExp} regexp
+   * @param {!Element} element
+   * @return {boolean} Whether any matches were found.
+   */
+  function highlightSelfMatches_(regExp, element) {
+    var found = false;
+    var walker = document.createTreeWalker(
+        element.shadowRoot, NodeFilter.SHOW_TEXT, null, false);
+
+    var node = walker.nextNode();
+    while (node) {
+      var textContent = node.nodeValue;
+      var tokens = textContent.split(regExp);
+
+      if (node.parentNode.tagName == 'STYLE' || tokens.length == 1) {
+        node = walker.nextNode();
+        continue;
+      }
+
+      var nextNode = walker.nextNode();
+      var parentNode = node.parentNode;
+      // Use existing node as placeholder to determine where to insert the
+      // replacement content.
+
+      var wrapper = document.createElement('span');
+      wrapper.classList.add(WRAPPER_CSS_CLASS);
+      parentNode.insertBefore(wrapper, node);
+
+      for (var i = 0; i < tokens.length; ++i) {
+        if (i % 2 == 0) {
+          wrapper.appendChild(document.createTextNode(tokens[i]));
+        } else {
+          fount = true;
+          var span = document.createElement('span');
+          span.classList.add(HIT_CSS_CLASS);
+          span.style['background-color'] = 'yellow';
+          span.textContent = tokens[i];
+          wrapper.appendChild(span);
+        }
+      }
+
+      // Remove old node.
+      node.remove();
+      node = nextNode;
+    }
+
+    return found;
+  }
+
+  /**
+   * Un-highlights all previous matches in the given element. It ignores
+   * children that have their own Shadow DOM.
+   * @param {!Element} element
+   */
+  function unhighlightSelfMatches_(element) {
+    var wrappers = element.shadowRoot.querySelectorAll('.' + WRAPPER_CSS_CLASS);
+    wrappers.forEach(function(wrapper) {
+      wrapperParent = wrapper.parentElement;
+      var elements = wrapper.querySelectorAll('.' + HIT_CSS_CLASS);
+      // For each element, remove the highlighting.
+      for (var i = 0; i < elements.length; i++) {
+        var node = elements[i];
+        wrapper.replaceChild(node.firstChild, node);
+      }
+
+      // Normalize so that adjacent text nodes will be combined.
+      wrapper.normalize();
+      // Restore the DOM structure as it was before the search occurred.
+      wrapperParent.appendChild(wrapper.firstChild);
+      wrapper.remove();
+    });
+  }
+
+  /**
+   * Highlights all matches (both within self and children's Shadow DOM).
+   * @param {!RegExp} regexp
+   * @param {!Element} element
+   */
+  function highlightMatches_(regexp, element) {
+    highlightSelfMatches_(regexp, element);
+    findChildren_(element).forEach(function(child) {
+      highlightMatches_(regexp, child);
+    });
+  }
+
+  /**
+   * Un-highlights all previous matches (both within self and children's Shadow
+   * DOM).
+   * @param {!Element} element
+   */
+  function unhighlightMatches_(element) {
+    unhighlightSelfMatches_(element);
+    findChildren_(element).forEach(unhighlightMatches_);
+  }
+
+  /**
+   * Performs hierarchical search, starting at the given element.
+   * @param {string} text
+   * @param {!Element} element
+   */
+  function search(text, element) {
+    unhighlightMatches_(element);
+
+    var searchText =
+        text.trim().toLowerCase().replace(/[-[\]{}()*+?.,\\^$|#\s]/g, '\\$&');
+    if (searchText.length == 0) {
+      return;
+    }
+
+    highlightMatches_(new RegExp('(' + searchText + ')', 'ig'), element);
+  }
+
+  window.search = search;
+})();