Make ManifestUpgradeDetectorTest use the intent version of WebApkInfo#create()

- This makes the tests more integration-test-like.
- This is a step towards merging ManifestUpgradeDetectorTest and
  WebApkUpdateManagerTest (See https://codereview.chromium.org/2460253002/)

BUG=639536

Review-Url: https://codereview.chromium.org/2543073005
Cr-Commit-Position: refs/heads/master@{#436326}
1 file changed