[AF Wallet Metadata] Simplify AutofillWalletMetadataSizeChecker again

This CL removes now unnecessary logic to avoid nested RunLoops. The
logic is not needed any more because the code does not use any run loops
any more.

The CL still leaves around a simplified version of the logic just to
allow DCHECKs.

Bug: 953152
Change-Id: I594f2b507ee3a3d0afa0fa61327ac2e506089f12
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1570831
Commit-Queue: Marc Treib <treib@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Auto-Submit: Jan Krcal <jkrcal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653150}
2 files changed