Revert "remove EH start delay" (microsoft#175315)

This reverts commit 21718a1.

re microsoft#175275

This change is still good but changes how/what we measure and we should do that with more slack time

Author: jrieken

src/vs/workbench/services/extensions/electron-sandbox/nativeExtensionService.ts

@@ -7,6 +7,7 @@ import { CachedExtensionScanner } from 'vs/workbench/services/extensions/electro
 import { AbstractExtensionService, ExtensionHostCrashTracker, ExtensionRunningPreference, extensionRunningPreferenceToString, filterByRunningLocation } from 'vs/workbench/services/extensions/common/abstractExtensionService';
 import * as nls from 'vs/nls';
 import * as performance from 'vs/base/common/performance';
+import { runWhenIdle } from 'vs/base/common/async';
 import { IWorkbenchEnvironmentService } from 'vs/workbench/services/environment/common/environmentService';
 import { IExtensionGalleryService } from 'vs/platform/extensionManagement/common/extensionManagement';
 import { IWorkbenchExtensionEnablementService, EnablementState, IWorkbenchExtensionManagementService } from 'vs/workbench/services/extensionManagement/common/extensionManagement';
@@ -116,7 +117,12 @@ export class NativeExtensionService extends AbstractExtensionService implements
 		// some editors require the extension host to restore
 		// and this would result in a deadlock
 		// see https://github.com/microsoft/vscode/issues/41322
-		lifecycleService.when(LifecyclePhase.Ready).then(() => this._initialize());
+		lifecycleService.when(LifecyclePhase.Ready).then(() => {
+			// reschedule to ensure this runs after restoring viewlets, panels, and editors
+			runWhenIdle(() => {
+				this._initialize();
+			}, 50 /*max delay*/);
+		});
 	}
 
 	private _isLocalWebWorkerEnabled(): [boolean, boolean] {