Roll pdfium deps.

It brings in these changes:
  e283e47 Convert source sets to static libraries.
  8b30162 Bring pdfium file in sync with chrome, fix mac build
  3b6c7e9 Move CPDF_Annot and CPDF_AnnotList to their own header.
  cc8ae2f Pass CPDF_Document instead of CPDF_AnnotList when constructing CPDF_Annot.
  69f160d Move CSSRuleCollection class to its own file
  47228ac Clean up singleton implementation
  31f8740 Rename remaining xfa_script_* files.
  c1515ef Rename the CScript_* files to match class names.
  8ca60b2 Use smart pointers for various Jbig2 decoding contexts
  5b36f0a Split xfa_object_imp into individual class files.

BUG=627637
TBR=jam@chromium.org

Review-Url: https://codereview.chromium.org/2166413002
Cr-Commit-Position: refs/heads/master@{#406894}

DEPS

@@ -56,7 +56,7 @@ 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': 'eea31b75a11215aa72a9845d47c38d2ce1edd4f7',
+  'pdfium_revision': 'e283e47aa3e6786dad94392db292e08ce18ccd5e',
   # 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.