All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=777849

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=ea96934f3896574a6f8f4bb3486960598a670c634b407b6820323636b0e88ecc


Bot(s) for this bug's original alert(s):

chromium-rel-mac11-pro

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/14fe2220f80000

📍 Couldn't reproduce a difference.
https://pinpoint-dot-chromeperf.appspot.com/job/14fe2220f80000

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/14eadb9b040000

bsalamon: Apologies the bisect didn't work earlier, looks like it reproed a significant page load time regression from you CL in october, https://skia-review.googlesource.com/60681, "Move clear-as-draw workaround to GrGLGpu and expose via GrContextOptions."

Can you take a look?

Given that these are all time to first paint, this is expected. I changed the implementation of an OpenGL driver bug workaround in way that requires an additional shader to be compiled. I'm going to leave this open, though, and tomorrow will check whether the driver bug has been fixed in newer MacOS versions. Then we could limit the workaround to older versions.

The following revision refers to this bug:
  https://skia.googlesource.com/skia/+/9a544bcab8ba8b032fdb5cd706cd88960502bec1

commit 9a544bcab8ba8b032fdb5cd706cd88960502bec1
Author: Brian Salomon <bsalomon@google.com>
Date: Wed Apr 04 20:54:48 2018

Stop using clear-as-draw workaround on newer Intel drivers on macOS

Bug=  chromium:777849 

Change-Id: I6276cbbf4bf6403ff9bf613d1fb31e56785a035e
Reviewed-on: https://skia-review.googlesource.com/118625
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>

[modify] https://crrev.com/9a544bcab8ba8b032fdb5cd706cd88960502bec1/src/gpu/gl/GrGLUtil.cpp
[modify] https://crrev.com/9a544bcab8ba8b032fdb5cd706cd88960502bec1/src/gpu/gl/GrGLUtil.h
[modify] https://crrev.com/9a544bcab8ba8b032fdb5cd706cd88960502bec1/src/gpu/gl/GrGLCaps.cpp

The workaround is off on Macs with sufficiently high Intel driver versions.