src/vs/platform/extensionManagement/node/extensionsWatcher.ts/ExtensionsWatcher/addInstalledExtension
class ExtensionsWatcher:	private addInstalledExtension(extension: IExtensionIdentifier): void {
		if (this.installedExtensions) {
			this.removeInstalledExtension(extension);
			this.installedExtensions.push(extension);
		}
	}