GTTF: Make our handling of Windows pre-processor symbols more consistent.

For example, there are differences between unit_tests and browser_tests,
which cause ridiculous problems when moving a test between those.

We're using the symbols anyway, so let's centralize it for maintainability.

TEST=compile
BUG=none

Review URL: http://codereview.chromium.org/3173044

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@57555 0039d316-1c4b-4281-b951-d872f2087c98
7 files changed