Roll src/third_party/pdfium/ a0ff010a3..ea3c3be83 (2 commits).

https://pdfium.googlesource.com/pdfium.git/+log/a0ff010a380c..ea3c3be83dae

$ git log a0ff010a3..ea3c3be83 --date=short --no-merges --format='%ad %ae %s'
2016-09-19 npm Remove duplicated charset definitions, and move them to fx_font.h
2016-09-19 stackexploit Fix compare between signed and unsigned values in CPDF_ImageRenderer::StartDIBSource.

BUG=645036

TBR=dsinclair@chromium.org

Review-Url: https://codereview.chromium.org/2349213002
Cr-Commit-Position: refs/heads/master@{#419466}

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': 'a0ff010a380c98d2092ff849ffc2f672e87fc799',
+  'pdfium_revision': 'ea3c3be83dae12ef682c68fc7cf906d790fd9f84',
   # 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.