[DevTools] Introduce EmulationModel which will encapsulate emulation

third_party/WebKit/Source/devtools/front_end/emulation/DeviceModeModel.js

 // Copyright 2015 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.
 /**
  * @implements {SDK.TargetManager.Observer}
  * @unrestricted
  */
 Emulation.DeviceModeModel = class {
   /**
    * @param {function()} updateCallback
@@ skipping 657 matching lines @@
     this._target.emulationAgent().resetViewport();
     this._calculateAndEmulate(false);
     return screenshot;
   }
 
   /**
    * @param {boolean} touchEnabled
    * @param {boolean} mobile
    */
   _applyTouch(touchEnabled, mobile) {
-    Emulation.MultitargetTouchModel.instance().setTouchEnabled(touchEnabled, mobile);
+    for (var emulationModel of SDK.targetManager.models(SDK.EmulationModel))
+      emulationModel.emulateTouch(touchEnabled, mobile);
   }
 };
 
 /** @enum {string} */
 Emulation.DeviceModeModel.Type = {
   None: 'None',
   Responsive: 'Responsive',
   Device: 'Device'
 };
 
 /** @enum {string} */
 Emulation.DeviceModeModel.UA = {
   Mobile: Common.UIString('Mobile'),
   MobileNoTouch: Common.UIString('Mobile (no touch)'),
   Desktop: Common.UIString('Desktop'),
   DesktopTouch: Common.UIString('Desktop (touch)')
 };
 
 Emulation.DeviceModeModel.MinDeviceSize = 50;
 Emulation.DeviceModeModel.MaxDeviceSize = 9999;
 
 
 Emulation.DeviceModeModel._defaultMobileUserAgent =
     'Mozilla/5.0 (Linux; Android 6.0; Nexus 5 Build/MRA58N) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/%s Mobile Safari/537.36';
 Emulation.DeviceModeModel._defaultMobileUserAgent =
     SDK.MultitargetNetworkManager.patchUserAgentWithChromeVersion(Emulation.DeviceModeModel._defaultMobileUserAgent);
 Emulation.DeviceModeModel.defaultMobileScaleFactor = 2;