Roll src/third_party/pdfium/ 39ee9dfac..917d24852 (1 commit).

https://pdfium.googlesource.com/pdfium.git/+log/39ee9dfac1c6..917d24852841

$ git log 39ee9dfac..917d24852 --date=short --no-merges --format='%ad %ae %s'
2016-09-22 tsepez Make CPDF_ColorSpace::Load() return a unique_ptr

TBR=dsinclair@chromium.org

Review-Url: https://codereview.chromium.org/2361333002
Cr-Commit-Position: refs/heads/master@{#420568}

DEPS

@@ -63,7 +63,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling PDFium
   # and whatever else without interference from each other.
-  'pdfium_revision': '39ee9dfac1c6d286a4075c7e2435fe1cfe365bad',
+  'pdfium_revision': '917d24852841f4919f418076c0277d2742f961ca',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling openmax_dl
   # and whatever else without interference from each other.