Break cyclic dependency between CertDatabase and NSSCertDatabase.
Before:
- CertDatabase::ObserveNSSCertDatabase(NSSCertDatabase* source) and implementation referenced NSSCertDatabase
- NSSCertDatabase() referenced CertDatabase::GetInstance()
Now:
- CertDatabase has no reference to NSSCertDatabase.
- NSSCertDatabase references CertDatabase.
BUG=NONE
Review URL: https://codereview.chromium.org/
370633003
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@282594 0039d316-1c4b-4281-b951-d872f2087c98