Predator and CL did not find any possible suspects.
Using Code Search for the file, "fx_skia_device.cpp" assigning to the concern owner who might be related.

@dsinclair -- Could you please look into the issue, kindly re-assign if this is not related to your changes.
Thank You.

Can you provide the command line to run this? pdfium_fuzzer doesn't appear as a chromium build, as far as I can tell. Is it in the pdfium tree?

No, it's in the chromium tree. 
See here how to build these binaries for actual fuzzing: 
https://chromium.googlesource.com/chromium/src/+/master/testing/libfuzzer/getting_started.md
but I don't think you need it just to reproduce the bug. 

Building the target pdfium_fuzzer in chromium should work. You'll need to build with ASAN enabled in order to repro the issue. Then run with: 

 ninja -C out/asan pdfium_fuzzer
 ASAN_OPTIONS="allocator_may_return_null=1:detect_leaks=1:detect_odr_violation=0" out/asan/pdfium_fuzzer ~/Downloads/clusterfuzz-testcase-6317611760746496

ClusterFuzz has detected this issue as fixed in range 459858:459906.

Detailed report: https://clusterfuzz.com/testcase?key=6317611760746496

Fuzzer: libfuzzer_pdfium_fuzzer
Job Type: libfuzzer_chrome_asan
Platform Id: linux

Crash Type: Indirect-leak
Crash Address: 
Crash State:
  CFX_SkiaDeviceDriver::StartDIBits
  CPDF_ImageRenderer::StartDIBSource
  CPDF_ImageRenderer::StartRenderDIBSource
  
Sanitizer: address (ASAN)

Regressed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan&range=458783:458809
Fixed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan&range=459858:459906

Reproducer Testcase: https://clusterfuzz.com/download/AMIfv94QDPcmextWH3QaiuayIqt025Xo70u9TzWl7tAEGqwoFsiin0rCdiKRB3S9S3LIf7S1-zk4o3P1jL1wOP4E7t412UaK4BDRW6tolZ2bharfwZrbPLlzJ6IO1LqQNkbVqtIavQuoiqkKf37h3JWtzXlOikhR0StX1-RA5wxTwJOVMWmrL0ZLo1CsHlIQhsW3QzniZEHMdJb5JkybjRVwdw-DhrrGVspPtmgKSFHd7dJnhXzbhCWYvXHsO3BWCbwlIPr8GXrOPjjzuSigD6clcOnIcoginnvhunEIZOYzhcbT89bNalmu7JRmZnPeMnoN7KMOmSVpptkrmYYNwp7IlkfIQiaOqTSqZqzdthlq1CyOC1J_O4275acj5CeOWqT8-v20l-BOhph5Z1xTMSU1IH_9iWJHGg?testcase_id=6317611760746496


See https://chromium.googlesource.com/chromium/src/+/master/testing/libfuzzer/reproducing.md for more information.

If you suspect that the result above is incorrect, try re-doing that job on the test case report page.

ClusterFuzz testcase 6317611760746496 is verified as fixed, so closing issue.

If this is incorrect, please add ClusterFuzz-Wrong label and re-open the issue.