Downloads libtensorflow and notifies via a callback when unpacked.
async function downloadLibtensorflow(callback) {
  // Ensure dependencies staged directory is available:
  await ensureDir(depsPath);

  console.warn('* Downloading libtensorflow');
  resources.downloadAndUnpackResource(
      getPlatformLibtensorflowUri(), depsPath, async () => {
        if (platform === 'win32') {
          // Some windows libtensorflow zip files are missing structure and the
          // eager headers. Check, restructure, and download resources as
          // needed.
          const depsIncludePath = path.join(depsPath, 'include');
          if (!await exists(depsLibTensorFlowPath)) {
            // Verify that tensorflow.dll exists
            const libtensorflowDll = path.join(depsPath, 'tensorflow.dll');
            if (!await exists(libtensorflowDll)) {
              throw new Error('Could not find libtensorflow.dll');
            }

            await ensureDir(depsLibPath);
            await rename(libtensorflowDll, depsLibTensorFlowPath);
          }

          // Next check the structure for the C-library headers. If they don't
          // exist, download and unzip them.
          if (!await exists(depsIncludePath)) {
            // Remove duplicated assets from the original libtensorflow package.
            // They will be replaced by the download below:
            await unlink(path.join(depsPath, 'c_api.h'));
            await unlink(path.join(depsPath, 'LICENSE'));

            // Download the C headers only and unpack:
            resources.downloadAndUnpackResource(
                TF_WIN_HEADERS_URI, depsPath, () => {
                  if (callback !== undefined) {
                    callback();
                  }
                });
          } else {
            if (callback !== undefined) {
              callback();
            }
          }
        } else {
          // No other work is required on other platforms.
          if (callback !== undefined) {
            callback();
          }
        }
      });
}