DevTools: implement release note behind an experiment

third_party/WebKit/Source/devtools/front_end/help/Help.js

+// Copyright 2017 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.
+
+/**
+ * @return {!Help.ReleaseNote}
+ */
+Help.latestReleaseNote = function() {
+  if (!Help._latestReleaseNote) {
+    /** @type {!Help.ReleaseNote} */
+    Help._latestReleaseNote = Help._getReleaseNoteByVersion(Help.browserVersion());
+  }
+  return Help._latestReleaseNote;
+};
+
+/**
+ * @param {number} version
+ * @return {!Help.ReleaseNote}
+ */
+Help._getReleaseNoteByVersion = function(version) {
+  var originalVersion = version;
+  while (version) {
+    var note = Help.releaseNoteText.find(note => note.version === version);
+    if (note)
+      return note;
+    version--;
+  }
+  console.error(`Unable to find release note for version ${originalVersion} - using last release note as fallback`);
+  return /** @type {!Help.ReleaseNote} */ (Help.releaseNoteText.peekLast());
+};
+
+/**
+ * @return {!Common.Setting}
+ */
+Help.releaseNoteVersionSetting = function() {
+  if (!Help._releaseNoteVersionSetting) {
+    /** @type {!Common.Setting} */
+    Help._releaseNoteVersionSetting = Common.settings.createSetting('releaseNoteVersionSeen', 0, false);
+  }
+  return Help._releaseNoteVersionSetting;
+};
+
+Help.showReleaseNoteIfNeeded = function() {
+  Help._showReleaseNoteIfNeeded(Help.releaseNoteVersionSetting().get(), Help.browserVersion());
+};
+
+/**
+ * @param {number} lastSeenVersion
+ * @param {number} browserVersion
+ */
+Help._showReleaseNoteIfNeeded = function(lastSeenVersion, browserVersion) {
+  if (!Runtime.experiments.isEnabled('releaseNote'))
+    return;
+  if (lastSeenVersion >= browserVersion)
+    return;
+  if (Help.latestReleaseNote().version !== browserVersion)
+    return;
+  Help.releaseNoteVersionSetting().set(Help.browserVersion());
+  UI.inspectorView.showPanel(Help._releaseNoteViewId);
+};
+
+/**
+ * @return {number}
+ */
+Help.browserVersion = function() {
+  if (!Help._browserVersion) {
+    var chromeRegex = new RegExp('(?:^|\\W)Chrome/(\\d+)');
+    var chromeMatch = navigator.userAgent.match(chromeRegex);
+    /** @type {number} */
+    Help._browserVersion = Number(chromeMatch[1]);
+  }
+  return Help._browserVersion;
+};
+
+/**
+ * @const
+ * @type {string}
+ */
+Help._releaseNoteViewId = 'release-note';
+
+/** @typedef {!{src: string}} */
+Help.ReleaseNoteImage;
+
+/** @typedef {!{text: string, link: string, featured: (boolean | undefined)}} */
+Help.ReleaseNoteHighlight;
+
+/**
+ * @typedef {!{version: number, highlights: !Array<!Help.ReleaseNoteHighlight>,
+ *    link: string, image: !Help.ReleaseNoteImage}}
+ */
+Help.ReleaseNote;