Roll src/third_party/pdfium/ 38fd84428..8f53f54a9 (1 commit).

https://pdfium.googlesource.com/pdfium.git/+log/38fd84428a1e..8f53f54a9cca

$ git log 38fd84428..8f53f54a9 --date=short --no-merges --format='%ad %ae %s'
2016-09-15 tsepez Add short-cut in CFX_{Byte,Wide}String::Operator<()

TBR=dsinclair@chromium.org

Review-Url: https://codereview.chromium.org/2345713003
Cr-Commit-Position: refs/heads/master@{#418967}

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': '38fd84428a1ea007a043be0b7d9b289e47aa5da0',
+  'pdfium_revision': '8f53f54a9ccada2ea8651f2786f1bbee323f09b7',
   # 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.