src/vs/workbench/api/common/extHostTask.ts/ExtHostTaskBase/registerTaskProvider
class ExtHostTaskBase:	public registerTaskProvider(extension: IExtensionDescription, type: string, provider: vscode.TaskProvider): vscode.Disposable {
		if (!provider) {
			return new types.Disposable(() => { });
		}
		const handle = this.nextHandle();
		this._handlers.set(handle, { type, provider, extension });
		this._proxy.$registerTaskProvider(handle, type);
		return new types.Disposable(() => {
			this._handlers.delete(handle);
			this._proxy.$unregisterTaskProvider(handle);
		});
	}