Prevent pdfium windows_xfa_clang builder from closing the tree.
Prevent pdfium windows_xfa_clang builder from closing the tree.

R=tsepez@chromium.org
TBR=dpranke@chromium.org

Review URL: https://codereview.chromium.org/1777133002

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@299205 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build