DevTools: implement release note behind an experiment

third_party/WebKit/Source/devtools/front_end/sdk/ConsoleModel.js

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 466 matching lines @@
   ConsoleAPI: 'console-api',
   Storage: 'storage',
   AppCache: 'appcache',
   Rendering: 'rendering',
   CSS: 'css',
   Security: 'security',
   Deprecation: 'deprecation',
   Worker: 'worker',
   Violation: 'violation',
   Intervention: 'intervention',
-  Other: 'other'
+  Other: 'other',

[luoe, 2017/02/11 00:30:54]

nit: commas at the end of the last entry should be consistent.  It looks like
this file excluded them before

 };
 
 /**
  * @enum {string}
  */
 SDK.ConsoleMessage.MessageType = {
   Log: 'log',
   Debug: 'debug',
   Info: 'info',
   Error: 'error',
@@ skipping 13 matching lines @@
   Command: 'command'
 };
 
 /**
  * @enum {string}
  */
 SDK.ConsoleMessage.MessageLevel = {
   Verbose: 'verbose',
   Info: 'info',
   Warning: 'warning',
-  Error: 'error'
+  Error: 'error',
+  Note: 'note',

[luoe, 2017/02/11 00:30:54]

I don't like how making release-notes a ConsoleViewMessage has introduced a note
'level' and 'type', making SDK aware of it.

If we want it viewported, can we try an alternative approach where we make a new
class that implements Console.ConsoleViewportElement, something like
Help.ConsoleHelpMessage?  It would require slight modification to ConsoleView's
itemCount, itemElement, fastHeight, but avoids touching ConsoleViewMessage at
all.

If we know that the help message is always going to be at the top, it could be
similar to the 'N messages hidden by filters' element that isn't viewported.  If
we end up wanting it to always be at the bottom, we can insert it after the
viewport but above the prompt.  wdyt?

 };
 
 /**
  * @param {!SDK.ConsoleMessage.MessageLevel} level
  * @return {number}
  */
 SDK.ConsoleMessage.MessageLevel.ordinal = function(level) {
   if (level === SDK.ConsoleMessage.MessageLevel.Verbose)
     return 0;
   if (level === SDK.ConsoleMessage.MessageLevel.Info)
@@ skipping 100 matching lines @@
    */
   _commandEvaluated(event) {
     this.dispatchEventToListeners(SDK.ConsoleModel.Events.CommandEvaluated, event.data);
   }
 };
 
 /**
  * @type {!SDK.MultitargetConsoleModel}
  */
 SDK.multitargetConsoleModel;