Roll src/third_party/pdfium/ 6708106e6..7e4e63b04 (1 commit).

https://pdfium.googlesource.com/pdfium.git/+log/6708106e6a3d..7e4e63b04f87

$ git log 6708106e6..7e4e63b04 --date=short --no-merges --format='%ad %ae %s'
2016-09-01 weili Revert of Fix leaked internal font (patchset #2 id:60001 of https://codereview.chromium.org/2297303004/ )

TBR=dsinclair@chromium.org

Review-Url: https://codereview.chromium.org/2303143002
Cr-Commit-Position: refs/heads/master@{#416171}

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': '6708106e6a3d54f3370c871ebf6643d1ecf58999',
+  'pdfium_revision': '7e4e63b04f87c690b017c43ebbb3218eb30c459a',
   # 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.