Add logging to gatekeeper opening reasons.
Add logging to gatekeeper opening reasons.

BUG=480001

Review URL: https://codereview.chromium.org/1097943005

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@295072 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build