Roll src/third_party/pdfium/ 380f53ec1..543651f9d (2 commits).

https://pdfium.googlesource.com/pdfium.git/+log/380f53ec1d0a..543651f9d8d8

$ git log 380f53ec1..543651f9d --date=short --no-merges --format='%ad %ae %s'
2016-09-01 thestig Do not download Linux sysroots.
2016-09-01 tsepez Make CPDF_ContentMark have a CPDF_ContentMarkData.

TBR=dsinclair@chromium.org

Review-Url: https://codereview.chromium.org/2299143003
Cr-Commit-Position: refs/heads/master@{#415957}

DEPS

@@ -60,7 +60,7 @@ 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': '380f53ec1d0a46648473e407934c9adede6cc1bd',
+  'pdfium_revision': '543651f9d8d8cb9ec45dce5fe3d06c2e6013de7d',
   # 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.