Fixing iframe jank in the local omnibox popup.

chrome/browser/resources/omnibox_result_loader.js

+// Copyright 2013 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.
+
+/**
+ * @fileoverview Orchestrates loading of suggestion content in several
+ * chrome-search://suggestion iframes.
+ */
+
+(function() {
+/**
+ * The origin of the embedding page.
+ * This string literal must be in double quotes for proper escaping.

[palmer, 2013/04/22 19:38:37]

I'm not a JS expert; why is that?

[Jered, 2013/04/22 23:02:58]

Because I'm using a JSON escaping function in Chrome, since it seemed like the
most robust way to escape a JS string in Chrome C++ code.

+ * @type {string}
+ * @const
+ */
+var EMBEDDER_ORIGIN = "{{ORIGIN}}";
+
+/**
+ * Converts an RGB color number to a hex color string if valid.
+ * @param {number} color A 6-digit hex RGB color code as a number.
+ * @return {?string} A CSS representation of the color or null if invalid.
+ */
+function convertColor(color) {
+  // Color must be a number, finite, with no fractional part, in the correct
+  // range for an RGB hex color.
+  if (isFinite(color) && Math.floor(color) == color &&
+      color >= 0 && color <= 0xffffff) {
+    var hexColor = color.toString(16);
+    // Pads with initial zeros and # (e.g. for 'ff' yields '#0000ff').
+    return '#000000'.substr(0, 7 - hexColor.length) + hexColor;
+  }
+  return null;
+}
+
+/**
+ * Checks and returns suggestion style.
+ * @param {!Object} pageStyle Instant page-specified overrides for suggestion
+ *     styles.
+ * @return {!Object} Checked styles or defaults.
+ */
+function getStyle(pageStyle) {
+  var apiHandle = chrome.embeddedSearch.searchBox;
+  var style = {
+    queryColor: '#000000',
+    urlColor: '#009933',
+    titleColor: '#666666',
+    font: apiHandle.font,
+    fontSize: apiHandle.fontSize
+  };
+  if ('queryColor' in pageStyle)
+    style.queryColor = convertColor(pageStyle.queryColor) || style.queryColor;
+  if ('urlColor' in pageStyle)
+    style.urlColor = convertColor(pageStyle.urlColor) || style.urlColor;
+  if ('titleColor' in pageStyle)
+    style.titleColor = convertColor(pageStyle.titleColor) || style.titleColor;
+  return style;
+}
+
+/**
+ * Renders a native history suggestion.
+ * @param {!Document} resultDoc The suggestion template document.
+ * @param {!Object} suggestion The NativeSuggestion to render.
+ * @param {!Object} pageStyle Page-specificed styles.
+ */
+function updateResult(resultDoc, suggestion, pageStyle) {
+  var style = getStyle(pageStyle);
+  resultDoc.body.style.fontSize = style.fontSize + 'px';
+  resultDoc.body.style.fontFamily = style.font;
+  var contentsNode = resultDoc.querySelector('#contents');
+  contentsNode.textContent = suggestion.contents;
+  contentsNode.style.color = suggestion.is_search ?
+      style.queryColor : style.urlColor;
+  var optionalNode = resultDoc.querySelector('#optional');
+  optionalNode.hidden = !suggestion.description;
+  if (suggestion.description) {
+    var titleNode = resultDoc.querySelector('#title');
+    titleNode.textContent = suggestion.description;
+    optionalNode.style.color = style.titleColor;
+  }
+}
+
+/**
+ * Handles a postMessage from the embedding page requesting to populate history
+ * suggestion iframes.
+ * @param {!Object} message The message.
+ */
+function handleMessage(message) {
+  // Only allow messages from the embedding page, which should be an Instant
+  // search provider or the local omnibox dropdown (and not e.g. a site which
+  // it has iframed.)
+  if (message.origin != EMBEDDER_ORIGIN)
+    return;
+
+  var apiHandle = chrome.embeddedSearch.searchBox;
+  if ('load' in message.data) {
+    for (var iframeId in message.data.load) {
+      var restrictedId = message.data.load[iframeId];
+      var suggestion = apiHandle.getSuggestionData(restrictedId);
+      var iframe = window.parent.frames[iframeId];
+      if (iframe)
+        updateResult(iframe.document, suggestion, message.data.style || {});
+    }
+    message.source.postMessage(
+        {loaded: message.data.requestId}, message.origin);
+  }
+}
+
+window.addEventListener('message', handleMessage, false);
+})();