The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0f56e9f394df98f278f6129e48adc0f88ef22899

commit 0f56e9f394df98f278f6129e48adc0f88ef22899
Author: James Darpinian <jdarpinian@chromium.org>
Date: Thu Jan 11 02:23:55 2018

Show GL errors in devtools when using passthrough cmd decoder.

GL errors are shown in the devtools console for WebGL contexts when
using the validating command decoder, but when we use the passthrough
command decoder and leave the validation to ANGLE, GL errors were not
shown. This change uses the KHR_debug extension to capture GL errors from
ANGLE and report them to the devtools console.

Bug:  800243 
Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel;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
Change-Id: I42717430c6ac0dfdae8c4180736ff91df6c26dcc
Reviewed-on: https://chromium-review.googlesource.com/856136
Commit-Queue: James Darpinian <jdarpinian@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#528536}
[modify] https://crrev.com/0f56e9f394df98f278f6129e48adc0f88ef22899/gpu/command_buffer/service/gl_utils.cc
[modify] https://crrev.com/0f56e9f394df98f278f6129e48adc0f88ef22899/gpu/command_buffer/service/gl_utils.h
[modify] https://crrev.com/0f56e9f394df98f278f6129e48adc0f88ef22899/gpu/command_buffer/service/gles2_cmd_decoder.cc
[modify] https://crrev.com/0f56e9f394df98f278f6129e48adc0f88ef22899/gpu/command_buffer/service/gles2_cmd_decoder_passthrough.cc
[modify] https://crrev.com/0f56e9f394df98f278f6129e48adc0f88ef22899/gpu/command_buffer/service/gles2_cmd_decoder_passthrough_doers.cc