Add retries for transient errors.
Add retries for transient errors.

R=djacques@chromium.org,stip@chromium.org
BUG=

Review URL: https://codereview.chromium.org/266573003

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@267332 0039d316-1c4b-4281-b951-d872f2087c98

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