Roll src/third_party/pdfium/ 303f9a3af..6312bf94b (6 commits)

https://pdfium.googlesource.com/pdfium.git/+log/303f9a3afc4a..6312bf94bb44

$ git log 303f9a3af..6312bf94b --date=short --no-merges --format='%ad %ae %s'
2018-05-02 hnakashima Use pointer instead of ref for XFA_RectWithoutMargin param.
2018-05-02 hnakashima Use pointer instead of ref for CXFA_Box::GetPathArcOrRounded param.
2018-05-02 hnakashima Use pointers instead of refs for GetPopupPos() params.
2018-05-02 rharrison Convert hand rolled buffer reader in CFX_MemoryStream
2018-05-02 hnakashima Transform in/out params from ref to pointer in CFX_(Txt|RTF)Break.
2018-05-02 hnakashima Transform in/out params from reference to pointer in CFDE_TextOut.

Created with:
  roll-dep src/third_party/pdfium


The AutoRoll server is located here: https://pdfium-roll.skia.org

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

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.


TBR=dsinclair@chromium.org

Change-Id: I7ff4a91f01a0adc5ed0af4ab7a91d89d0c540151
Reviewed-on: https://chromium-review.googlesource.com/1040736
Commit-Queue: pdfium-chromium-autoroll <pdfium-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Reviewed-by: pdfium-chromium-autoroll <pdfium-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#555583}

DEPS

@@ -120,7 +120,7 @@ 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': '303f9a3afc4a86147213d4ac57894480485090a2',
+  'pdfium_revision': '6312bf94bb44e2edeb855008da0921c13103f66a',
   # 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.