ClientCertStoreWin: do client cert and key lookup on SSLPlatformKeyTaskRunner.

When USE_BYTE_CERTS=true and X509Certificate is no longer holding PCCERT_CONTEXT handles, it is safe to move these off the IO thread.

BUG=394131

Review-Url: https://codereview.chromium.org/2927193003
Cr-Commit-Position: refs/heads/master@{#481309}
2 files changed