It appears that KeyCredentialManager.RequestCreateAsync in the WinRT
API does not like key names that contain forward slashes, which we are
sometimes providing as a result of base64-encoding random data for the
names.
This changes switches key names to hex encoding.
It also adds metrics recording for the success of that function, and
RequestSignAsync also.
Bug: 40274370
Change-Id: Ie502ef52db99edc709c4e57844de46621edbe6ab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5534415
Reviewed-by: Adam Langley <agl@chromium.org>
Commit-Queue: Ken Buchanan <kenrb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1300332}
61a2d119d7