DevTools: allow capturing screenshots from command menu.

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 618 matching lines @@
    */
   async captureScreenshot(fullSize) {
     var screenCaptureModel = this._target ? this._target.model(SDK.ScreenCaptureModel) : null;
     if (!screenCaptureModel)
       return null;
 
     var metrics = await screenCaptureModel.fetchLayoutMetrics();
     if (!metrics)
       return null;
 
+    if (!this._emulatedPageSize)
+      this._calculateAndEmulate(false);
+    this._target.renderingAgent().setShowViewportSizeOnResize(false);
+
     var pageSize = fullSize ? new UI.Size(metrics.contentWidth, metrics.contentHeight) : this._emulatedPageSize;
     var promises = [];
     promises.push(
         this._target.emulationAgent().setVisibleSize(Math.floor(pageSize.width), Math.floor(pageSize.height)));
     if (fullSize) {
       promises.push(this._target.emulationAgent().forceViewport(0, 0, 1));
     } else {
       promises.push(this._target.emulationAgent().forceViewport(
           Math.floor(metrics.viewportX), Math.floor(metrics.viewportY), metrics.viewportScale));
     }
@@ skipping 46 matching lines @@
 
 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;