DevTools: implement release note behind an experiment

third_party/WebKit/Source/devtools/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/features.gni")
 import("//third_party/WebKit/public/public_features.gni")
 import("//third_party/WebKit/Source/core/core.gni")
 
 all_devtools_files = [
   "front_end/accessibility/AccessibilityModel.js",
@@ skipping 228 matching lines @@
   "front_end/heap_snapshot_model/HeapSnapshotModel.js",
   "front_end/heap_snapshot_model/module.json",
   "front_end/heap_snapshot_worker.js",
   "front_end/heap_snapshot_worker.json",
   "front_end/heap_snapshot_worker/AllocationProfile.js",
   "front_end/heap_snapshot_worker/HeapSnapshot.js",
   "front_end/heap_snapshot_worker/HeapSnapshotLoader.js",
   "front_end/heap_snapshot_worker/HeapSnapshotWorker.js",
   "front_end/heap_snapshot_worker/HeapSnapshotWorkerDispatcher.js",
   "front_end/heap_snapshot_worker/module.json",
+  "front_end/help/Help.js",
+  "front_end/help/module.json",
+  "front_end/help/releaseNote.css",
+  "front_end/help/ReleaseNote.js",
+  "front_end/help/ReleaseNoteText.js",
   "front_end/host/InspectorFrontendHost.js",
   "front_end/host/InspectorFrontendHostAPI.js",
   "front_end/host/module.json",
   "front_end/host/Platform.js",
   "front_end/host/ResourceLoader.js",
   "front_end/host/UserMetrics.js",
   "front_end/inline_editor/bezierEditor.css",
   "front_end/inline_editor/BezierEditor.js",
   "front_end/inline_editor/bezierSwatch.css",
   "front_end/inline_editor/BezierUI.js",
@@ skipping 834 matching lines @@
     ".eslintrc.js",
     "devtools-node-modules/",
     "front_end/",
     "scripts/buildbot/run_eslint.py",
     "scripts/local_node/",
     "//testing/scripts/common.py",
     "//testing/scripts/run_devtools_check.py",
     "//testing/xvfb.py",
   ]
 }