Add missing test files to libchrome_test_helpers library

Some code (like libweave) depends on more libchorme test functionality
(e.g. gtest's printer for base::FilePath for example). Re-added
the test files which used to be in libchrome-test target on Chrome OS.

BUG:22948980
Change-Id: Id11af3a4eb3c1794185027d180d7caa5eea5eda5
1 file changed