Roll src/third_party/pdfium/ e4d611c9c..48f776f7e (2 commits).

https://pdfium.googlesource.com/pdfium.git/+log/e4d611c9c6d8..48f776f7e801

$ git log e4d611c9c..48f776f7e --date=short --no-merges --format='%ad %ae %s'
2017-01-05 npm Remove unused CPDF_ImageCacheEntry::GetCachedBitmap
2017-01-05 tsepez remove unused CFX_PtrToInt32 typedef

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, see:
http://www.chromium.org/developers/tree-sheriffs/sheriff-details-chromium#TOC-Failures-due-to-DEPS-rolls

TBR=dsinclair@chromium.org

Review-Url: https://codereview.chromium.org/2615923002
Cr-Commit-Position: refs/heads/master@{#441757}

DEPS

@@ -64,7 +64,7 @@ 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': 'e4d611c9c6d882bd47b6936554bdfc5c1ea614a0',
+  'pdfium_revision': '48f776f7e801d719683b251dc21ee8c0e3250d90',
   # 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.