DevTools: [Audits] Fix race during emulation state reset

Updated emulation state is applied in stopAndReattach, 
but that was racing against the state being reset within
hideDialog. 

Bug: 747245
Change-Id: I1c1698525691f37d4c988349cd7bc84a23a3e7f6
Reviewed-on: https://chromium-review.googlesource.com/592464Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Commit-Queue: Paul Irish <paulirish@chromium.org>
Cr-Commit-Position: refs/heads/master@{#490624}

third_party/WebKit/Source/devtools/front_end/audits2/Audits2Panel.js

@@ -310,11 +310,6 @@ Audits2.Audits2Panel = class extends UI.Panel {
       return;
     this._dialog.hide();
 
-    var emulationModel = self.singleton(Emulation.DeviceModeModel);
-    emulationModel.enabledSetting().set(this._emulationEnabledBefore);
-    emulationModel.deviceOutlineSetting().set(this._emulationOutlineEnabledBefore);
-    emulationModel.toolbarControlsEnabledSetting().set(true);
-
     delete this._dialog;
     delete this._statusView;
     delete this._statusIcon;
@@ -368,7 +363,13 @@ Audits2.Audits2Panel = class extends UI.Panel {
    */
   async _stopAndReattach() {
     await this._protocolService.detach();
+
+    var emulationModel = self.singleton(Emulation.DeviceModeModel);
+    emulationModel.enabledSetting().set(this._emulationEnabledBefore);
+    emulationModel.deviceOutlineSetting().set(this._emulationOutlineEnabledBefore);
+    emulationModel.toolbarControlsEnabledSetting().set(true);
     Emulation.InspectedPagePlaceholder.instance().update(true);
+
     Host.userMetrics.actionTaken(Host.UserMetrics.Action.Audits2Finished);
     var resourceTreeModel = SDK.targetManager.mainTarget().model(SDK.ResourceTreeModel);
     // reload to reset the page state