Took a crack at it here: https://codereview.chromium.org/1752183002/

 bug 591248  is about bundling libFuzzer from clang; this one is about building it in parallel. Do we need both?

Do you mean  bug 543318  ?

I think the situation has changed (kcc, aizatsky, please correct me if I'm wrong) -- libFuzzer is no longer tightly integrated with LLVM, so it will no longer make sense to bundle it with clang.

Yes. Rather than bundling it with clang we'd prefer to pull it in as a normal third party dep.

 Issue 591479  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/cbd1cf202d289ccaf76aa67828e9425e5a061d6b

commit cbd1cf202d289ccaf76aa67828e9425e5a061d6b
Author: ochang <ochang@chromium.org>
Date: Fri Apr 01 21:37:37 2016

Pull in libFuzzer as a third party dep.

This makes it so that developers no longer have to build
clang locally to get libFuzzer.

R=thakis@chromium.org,aizatsky@chromium.org
BUG= 591248 , 598448 

# Previous patchset passed CQ bots, but had a trivial conflict when
# trying to apply because of catapult roll.
NOTRY=true

Review URL: https://codereview.chromium.org/1752183002

Cr-Commit-Position: refs/heads/master@{#384692}

[modify] https://crrev.com/cbd1cf202d289ccaf76aa67828e9425e5a061d6b/.gitignore
[modify] https://crrev.com/cbd1cf202d289ccaf76aa67828e9425e5a061d6b/DEPS
[modify] https://crrev.com/cbd1cf202d289ccaf76aa67828e9425e5a061d6b/testing/libfuzzer/BUILD.gn
[add] https://crrev.com/cbd1cf202d289ccaf76aa67828e9425e5a061d6b/third_party/libFuzzer/BUILD.gn
[add] https://crrev.com/cbd1cf202d289ccaf76aa67828e9425e5a061d6b/third_party/libFuzzer/LICENSE.TXT
[add] https://crrev.com/cbd1cf202d289ccaf76aa67828e9425e5a061d6b/third_party/libFuzzer/OWNERS
[add] https://crrev.com/cbd1cf202d289ccaf76aa67828e9425e5a061d6b/third_party/libFuzzer/README.chromium
[modify] https://crrev.com/cbd1cf202d289ccaf76aa67828e9425e5a061d6b/tools/checklicenses/checklicenses.py