It looks like this is new behavior. https://build.chromium.org/p/chromium.gpu.fyi/builders/Mac%2010.10%20Retina%20Debug%20%28AMD%29/builds/10984 is the first build that seemed to fail in this way.

Is there any indication why this might have started happening? Was the test on the verge of timing out, and was it just pushed over a threshold?

Looks like it has always taken a long time, at least comapred to the other tests, even on the Windows bots this test takes quite a while.

Is there an easy way to raise the timeout?  40 seconds for a test still seems reasonable.

Not sure -- I haven't looked at that harness in a while. Can you dig a little deeper?

Will do

Jamie found that the gtest timeout is coming from this constant: https://cs.chromium.org/chromium/src/base/test/test_timeouts.cc?sq=package:chromium&dr=C&rcl=1473923811&l=75

We could either increase the constant or skip this test on debug configurations.  I'd be comfortable with skipping.  Thoughts?

Seems fine to me to skip it in debug configurations since it's so slow. Possible for you to put up a CL implementing this?

Yep, PTAL: https://codereview.chromium.org/2346883002/

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b03d43e3f56b003f1f0d890e8bcb35fa0ce7b5b2

commit b03d43e3f56b003f1f0d890e8bcb35fa0ce7b5b2
Author: geofflang <geofflang@chromium.org>
Date: Thu Sep 15 21:54:09 2016

Skip GLES2ConformTest.GL2FixedTests_buffer_color_input_run on debug

This test doesn't run fast enough to always finish within the hard-coded 45 second time limit.

R=kbr@chromium.org
TBR=piman@chromium.org

BUG= 646442 
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2346883002
Cr-Commit-Position: refs/heads/master@{#418996}

[modify] https://crrev.com/b03d43e3f56b003f1f0d890e8bcb35fa0ce7b5b2/gpu/gles2_conform_support/gles2_conform_test_expectations.txt