src/vs/workbench/api/common/extHostOutput.ts/ExtHostOutputService/createExtensionLogDirectory
class ExtHostOutputService:	private createExtensionLogDirectory(extension: IExtensionDescription): Thenable<URI> {
		let extensionLogDirectoryPromise = this.extensionLogDirectoryPromise.get(extension.identifier.value);
		if (!extensionLogDirectoryPromise) {
			const extensionLogDirectory = this.extHostFileSystemInfo.extUri.joinPath(this.initData.logsLocation, extension.identifier.value);
			this.extensionLogDirectoryPromise.set(extension.identifier.value, extensionLogDirectoryPromise = (async () => {
				try {
					await this.extHostFileSystem.value.createDirectory(extensionLogDirectory);
				} catch (err) {
					if (toFileSystemProviderErrorCode(err) !== FileSystemProviderErrorCode.FileExists) {
						throw err;
					}
				}
				return extensionLogDirectory;
			})());
		}
		return extensionLogDirectoryPromise;
	}