GitLab

This CL adds test cases for google_apis::GetAboutOperation.
Also, it naturally introduces the testing base code for the operations
communicating with a drive api server, so that it will be reused for unit tests
of other operation classes in drive_api_operations.{h,cc} later.

BUG=162155
TEST=Ran unit_tests


Review URL: https://chromiumcodereview.appspot.com/11824023

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@176066 0039d316-1c4b-4281-b951-d872f2087c98