Properly report fxc.exe errors.

fxc.exe does not produce output if it fails to execute because, for example, one of its needed DLLs is not executable. It does return a non-success exit code, however. Fail the build step when that happens.

BUG=None

Review URL: https://codereview.chromium.org/107363005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242968 0039d316-1c4b-4281-b951-d872f2087c98
Don't crash when token info is not found, which can happen if
AboutSigninInternals is initialized after token request.

BUG=331590

TBR=rogerta
NOTRY=true

Review URL: https://codereview.chromium.org/117583004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242969 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242968
SVN changes up to revision 242969