I admit that this work fell on you on a short notice (which in turn was a miscommunication between our teams). But I'm still afraid we don't have capacity to implement the chrome part (only to consult and add things to compiler-rt, if needed)

The old design had lots of complexity because it needed to jump hoops between compiler-rt and chrome. 
The new coverage simply has *no* compiler-rt component as far as chrome is concerned  (there are simple weak definitions of callbacks in compiler-rt, but chrome will simply need to redefine them). So, hopefully, the chrome part will actually be simpler than the previous code in compiler-rt. 

And I had to move "quickly" with removing the old coverage support because the old code was literally unmaintanable and was blocking me from performance improvements in coverage for libFuzzer. 

I'll own this for now, but unfortunately won't be able to get to it likely until Q3.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ae28b08add10e81782b81e04c083425ca0bd42c9

commit ae28b08add10e81782b81e04c083425ca0bd42c9
Author: Oliver Chang <ochang@chromium.org>
Date: Mon Jun 12 20:46:19 2017

Remove sandboxed sanitizer coverage support code for Linux.

This will need to be reimplemented later using
__sanitizer_cov_trace_pc_guard.

BUG= 728684 , 729822 

Change-Id: I1f979b3ceac8a59e27f96428b77ec1d983ac4cef
Reviewed-on: https://chromium-review.googlesource.com/529972
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: Oliver Chang <ochang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#478748}
[modify] https://crrev.com/ae28b08add10e81782b81e04c083425ca0bd42c9/content/gpu/gpu_main.cc
[modify] https://crrev.com/ae28b08add10e81782b81e04c083425ca0bd42c9/content/zygote/zygote_main_linux.cc

This is no longer needed, and superceded by clang source based coverage.