[DevTools] Initial implementation of device modes.

Source/devtools/front_end/main/Main.js

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2007 Matt Lilek (pewtermoose@gmail.com).
  * Copyright (C) 2009 Joseph Pecoraro
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
@@ skipping 109 matching lines @@
      * @param {!Object<string, string>} prefs
      */
     _initializeExperiments: function(prefs)
     {
         Runtime.experiments.register("accessibilityInspection", "Accessibility Inspection");
         Runtime.experiments.register("animationInspection", "Animation Inspection");
         Runtime.experiments.register("applyCustomStylesheet", "Allow custom UI themes");
         Runtime.experiments.register("blackboxJSFramesOnTimeline", "Blackbox JavaScript frames on Timeline");
         Runtime.experiments.register("timelineDetailsChart", "Costly functions view in Timeline details", true);
         Runtime.experiments.register("customObjectFormatters", "Custom object formatters", true);
+        Runtime.experiments.register("deviceModes", "Device variations in Device Mode", true);
         Runtime.experiments.register("emptySourceMapAutoStepping", "Empty sourcemap auto-stepping");
         Runtime.experiments.register("fileSystemInspection", "FileSystem inspection");
         Runtime.experiments.register("filmStripInNetworkAndTimeline", "Filmstrip in Network and Timeline Panel", true);
         Runtime.experiments.register("frameRateOnEventsOverview", "Frame rate on Timeline events overview", true);
         Runtime.experiments.register("gpuTimeline", "GPU data on timeline", true);
         Runtime.experiments.register("inputEventsOnTimelineOverview", "Input events on Timeline overview", true)
         Runtime.experiments.register("layersPanel", "Layers panel");
         Runtime.experiments.register("materialDesign", "Material design");
         Runtime.experiments.register("networkRequestHeadersFilterInDetailsView", "Network request headers filter in details view", true);
         Runtime.experiments.register("networkRequestsOnTimeline", "Network requests on Timeline");
@@ skipping 697 matching lines @@
     p.classList.add("help-section");
     p.textContent = WebInspector.UIString("Inspected worker has terminated. Once it restarts we will attach to it automatically.");
 }
 
 WebInspector.WorkerTerminatedScreen.prototype = {
 
     __proto__: WebInspector.HelpScreen.prototype
 }
 
 new WebInspector.Main();