Roll src/third_party/pdfium/ fd670fdef..696fc8b70 (6 commits).
Roll src/third_party/pdfium/ fd670fdef..696fc8b70 (6 commits).

https://pdfium.googlesource.com/pdfium.git/+log/fd670fdef898..696fc8b70c19

$ git log fd670fdef..696fc8b70 --date=short --no-merges --format='%ad %ae %s'
2016-05-04 dsinclair Revert of Remove unneeded CPVT classes. (patchset #7 id:140001 of https://codereview.chromium.org/1919283008/ )
2016-05-04 tsepez Replace IFX_MemoryAllocator::Release() with delete.
2016-05-04 tsepez Remove unused CFX_CPLTree<> template
2016-05-03 tsepez Cleanup XFA-Specific memory allocators.
2016-05-03 dsinclair Remove FWL_WGTHITTEST_* defines in favour of enum class.
2016-05-03 weili Revert of Relax a couple checks to allow certain non-standard PDF files. (patchset #1 id:1 of https://codereview.chromium.org/1926823002/ )

BUG=chromium:608901

Review-Url: https://codereview.chromium.org/1946263002
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#391537}

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk