Merge to XFA: Remove duplicate core/include/thirdparties headers.

Review URL: https://codereview.chromium.org/1417483004 .
(cherry picked from commit ad0f4d9b371c1862a78046c2e3dea5d515043070)

TBR=thestig@chromium.org

Review URL: https://codereview.chromium.org/1418543003 .
7 files changed