Fix time zone handling for git time stamps.
Fix time zone handling for git time stamps.

BUG=398846
R=kmg@chromium.org,mmoss@chromium.org,iannucci@chromium.org

Review URL: https://codereview.chromium.org/428213003

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@286559 0039d316-1c4b-4281-b951-d872f2087c98

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