This is failing on Windows as well:

https://build.chromium.org/p/chromium.gpu.fyi/builders/Win7%20Debug%20%28AMD%29/builds/3010
https://build.chromium.org/p/chromium.gpu.fyi/builders/Win7%20Debug%20%28NVIDIA%29/builds/21577

gpu_process_launch_tests is also failing on Windows related to this roll:

Unexpected Failures:
* gpu_tests.gpu_process_integration_test.GpuProcessIntegrationTest.GpuProcess_swiftshader_for_webgl

Failing on Linux too:

https://luci-milo.appspot.com/buildbot/chromium.gpu.fyi/Linux%20Debug%20%28NVIDIA%29/39270

Log excerpt follows. I'm reverting the roll.

[ RUN      ] SwiftShaderTest.Initalization
swiftshader_unittests: ../../third_party/swiftshader/src/OpenGL/libGLESv2/utilities.cpp:1836: unsigned int sw2es::GetDepthSize(sw::Format): Assertion `false' failed.
Received signal 6
#0 0x7f8419959f2d base::debug::StackTrace::StackTrace()
#1 0x7f84199582fc base::debug::StackTrace::StackTrace()
#2 0x7f84199598e5 base::debug::(anonymous namespace)::StackDumpSignalHandler()
#3 0x7f8419dd0330 <unknown>
#4 0x7f8418a2dc37 gsignal
#5 0x7f8418a31028 abort
#6 0x7f8418a26bf6 <unknown>
#7 0x7f8418a26ca2 __assert_fail
#8 0x7f841953453c sw2es::GetDepthSize()
#9 0x7f84195029db es2::DefaultFramebuffer::DefaultFramebuffer()
#10 0x7f84194f4fa2 es2::Context::makeCurrent()
#11 0x7f841a1ccd29 egl::MakeCurrent()
#12 0x000000411253 SwiftShaderTest_Initalization_Test::TestBody()
#13 0x0000004910de testing::internal::HandleSehExceptionsInMethodIfSupported<>()
#14 0x000000480962 testing::internal::HandleExceptionsInMethodIfSupported<>()
#15 0x00000046ae46 testing::Test::Run()
#16 0x00000046b99d testing::TestInfo::Run()
#17 0x00000046c40c testing::TestCase::Run()
#18 0x00000047806c testing::internal::UnitTestImpl::RunAllTests()
#19 0x000000491e2e testing::internal::HandleSehExceptionsInMethodIfSupported<>()
#20 0x000000482082 testing::internal::HandleExceptionsInMethodIfSupported<>()
#21 0x000000477caa testing::UnitTest::Run()
#22 0x000000495fd1 RUN_ALL_TESTS()
#23 0x000000493a9e base::TestSuite::Run()
#24 0x00000040e853 (anonymous namespace)::RunHelper()
#25 0x00000040ecd5 _ZN4base8internal13FunctorTraitsIPFiPNS_9TestSuiteEEvE6InvokeIJS3_EEEiS5_DpOT_
#26 0x00000040ec70 _ZN4base8internal12InvokeHelperILb0EiE8MakeItSoIRKPFiPNS_9TestSuiteEEJS5_EEEiOT_DpOT0_
#27 0x00000040ec35 _ZN4base8internal7InvokerINS0_9BindStateIPFiPNS_9TestSuiteEEJNS0_17UnretainedWrapperIS3_EEEEEFivEE7RunImplIRKS6_RKNSt3__15tupleIJS8_EEEJLm0EEEEiOT_OT0_NSF_16integer_sequenceImJXspT1_EEEE
#28 0x00000040eb4c _ZN4base8internal7InvokerINS0_9BindStateIPFiPNS_9TestSuiteEEJNS0_17UnretainedWrapperIS3_EEEEEFivEE3RunEPNS0_13BindStateBaseE
#29 0x0000004976cd _ZNKR4base17RepeatingCallbackIFvvEE3RunEv
#30 0x000000498577 base::(anonymous namespace)::LaunchUnitTestsInternal()
#31 0x0000004989e8 base::LaunchUnitTestsWithOptions()
#32 0x00000040e7a5 main
#33 0x7f8418a18f45 __libc_start_main
#34 0x00000040e5bf <unknown>
  r8: fffffffffffffed8  r9: fffffffffffffec8 r10: 0000000000000008 r11: 0000000000000202
 r12: 00007f84197608ed r13: 00007f841976b65b r14: 000032e3ad4dd2c0 r15: 000032e3ad0b8160
  di: 00000000000052ce  si: 00000000000052ce  bp: 00007f8418b773b8  bx: 00007f841a1fa000
  dx: 0000000000000006  ax: 0000000000000000  cx: ffffffffffffffff  sp: 00007ffc6be1b1a8
  ip: 00007f8418a2dc37 efl: 0000000000000202 cgf: 0000000000000033 erf: 0000000000000000
 trp: 0000000000000000 msk: 0000000000000000 cr2: 0000000000000000
[end of stack trace]
Calling _exit(1). Core file will not be generated.
[21196:21197:0915/165325.728736:5200827143:ERROR:kill_posix.cc(83)] Unable to terminate process group 21198: No such process (3)
[1/1] SwiftShaderTest.Initalization (CRASHED)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/599a29e3a1d04ab6c36fea6a2b2b6cb52458a986

commit 599a29e3a1d04ab6c36fea6a2b2b6cb52458a986
Author: Kenneth Russell <kbr@chromium.org>
Date: Sat Sep 16 16:02:49 2017

Revert "Roll SwiftShader 0def102..3cbeac5"

This reverts commit bdc4a07bbd2974e9722a17c24f210a4e7b8840ae.

Reason for revert: caused crashes on all Debug bots running SwiftShader unittests. See  http://crbug.com/765912  .

BUG= 765912 

Original change's description:
> Roll SwiftShader 0def102..3cbeac5
> 
> https://swiftshader.googlesource.com/SwiftShader.git/+log/0def102..3cbeac5
> 
> BUG= swiftshader:82 
> 
> TBR=kbr@chromium.org
> 
> Change-Id: If47b0afbe3255dbe508b07769a0b33aa9c5216c0
> Reviewed-on: https://chromium-review.googlesource.com/669306
> Reviewed-by: Alexis Hétu <sugoi@chromium.org>
> Commit-Queue: Nicolas Capens <nicolascapens@google.com>
> Cr-Commit-Position: refs/heads/master@{#502392}

TBR=sugoi@chromium.org,nicolascapens@google.com

Change-Id: I689913881177ec976fef91671ef8da0f96adb2a5
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug:  swiftshader:82 
Reviewed-on: https://chromium-review.googlesource.com/670021
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#502504}
[modify] https://crrev.com/599a29e3a1d04ab6c36fea6a2b2b6cb52458a986/DEPS

Thanks for the detailed report and the quick action.

The following revision refers to this bug:
  https://swiftshader.googlesource.com/SwiftShader.git/+/1de0eb7b300e8ed7fea035f6f680f6cba2720f8c

commit 1de0eb7b300e8ed7fea035f6f680f6cba2720f8c
Author: Nicolas Capens <capn@google.com>
Date: Mon Sep 18 15:38:08 2017

Fix implementation format for default renderbuffer.

The spec defines that the initial state for a newly bound renderbuffer
has a format of RGBA4. However, when querying the number of red/green/
blue/alpha/depth/stencil bits, we should report the actual number of
bits allocated (0), and not assert.

 Bug chromium:765912 
Bug b/25351344

Change-Id: Icc3eb59e76bcbd6f0f2f16a2a75ace706ae17251
Reviewed-on: https://swiftshader-review.googlesource.com/12148
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>

[modify] https://crrev.com/1de0eb7b300e8ed7fea035f6f680f6cba2720f8c/src/OpenGL/libGLESv2/Renderbuffer.cpp
[modify] https://crrev.com/1de0eb7b300e8ed7fea035f6f680f6cba2720f8c/src/OpenGL/libGLESv2/utilities.cpp