Gate building jsoncpp_fuzzer on |build_with_chromium|

Projects which depend on third_party/jsoncpp that are not built in
a Chromium checkout may not have the //testing/libfuzzer dependencies
needed to build jsoncpp_fuzzer.

TBR=chromium-third-party@google.com

Bug: dawn:208
Change-Id: I4664cca2a975fe52013ad7874db8e098ccbb6098
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1861014
Commit-Queue: Austin Eng <enga@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#706932}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: a32363664a729129364b057ab8377e047aaff093
1 file changed
tree: d8e90c4941b26f76385c786b829aa4a46449cdc4
  1. BUILD.gn
  2. LICENSE
  3. OWNERS
  4. README.chromium
  5. fuzzers/
  6. generated/