src/vs/platform/userDataSync/common/keybindingsSync.ts/KeybindingsSynchroniser/toSyncContent
class KeybindingsSynchroniser:	private toSyncContent(keybindingsContent: string, syncContent?: string): string {
		let parsed: ISyncContent = {};
		try {
			parsed = JSON.parse(syncContent || '{}');
		} catch (e) {
			this.logService.error(e);
		}
		if (this.syncKeybindingsPerPlatform()) {
			delete parsed.all;
		} else {
			parsed.all = keybindingsContent;
		}
		switch (OS) {
			case OperatingSystem.Macintosh:
				parsed.mac = keybindingsContent;
				break;
			case OperatingSystem.Linux:
				parsed.linux = keybindingsContent;
				break;
			case OperatingSystem.Windows:
				parsed.windows = keybindingsContent;
				break;
		}
		return JSON.stringify(parsed);
	}