cancel-download.java

class AppDownload {
	WebExtension.DownloadItem mExtensionDownload;

	// Cancels the download
	GeckoResult<Void> cancel() {
		// Actually cancel the download

		// Notifies extension
		return mExtensionDownload.update().canceled(true).commit();
	}

	void setDownloadItem(DownloadItem item) {
		mExtensionDownload = item;
	}
}

class AppDownloadController {
	// stuff ...
	
	@Override
	onCancel(DownloadItem item, WebExtension extension) {
		AppDownload download = mDownloads.byDownloadItem(item);
		// Update the download item in case it's out of date
		download.setDownloadItem(item);
		return download.cancel();
	}
}

// UI Code

onClick() {
	mDownload.cancel();
}