src/vs/platform/userDataSync/common/userDataAutoSyncService.ts/AutoSync/sync
class AutoSync:	sync(reason: string, disableCache: boolean): Promise<void> {
		const syncPromise = createCancelablePromise(async token => {
			if (this.syncPromise) {
				try {
					// Wait until existing sync is finished
					this.logService.debug('Auto Sync: Waiting until sync is finished.');
					await this.syncPromise;
				} catch (error) {
					if (isCancellationError(error)) {
						// Cancelled => Disposed. Donot continue sync.
						return;
					}
				}
			}
			return this.doSync(reason, disableCache, token);
		});
		this.syncPromise = syncPromise;
		this.syncPromise.finally(() => this.syncPromise = undefined);
		return this.syncPromise;
	}