Confirmed. Local build results:

ACTION //third_party/angle/src/vulkan_support:sp...nal_revision_generate(//build/toolchain/win:win_clang_x64)
FAILED: gen/third_party/angle/src/vulkan_support/angle/vulkan/spirv_tools_commit_id.h
C:/depot_tools/win_tools-2_7_6_bin/python/bin/python.exe ../../third_party/vulkan-validation-layers/src/scripts/external_revision_generator.py ../../third_party/spirv-tools-angle/src SPIRV_TOOLS_COMMIT_ID gen/third_party/angle/src/vulkan_support/angle/vulkan/spirv_tools_commit_id.h
Traceback (most recent call last):
  File "../../third_party/vulkan-validation-layers/src/scripts/external_revision_generator.py", line 38, in <module>
    commit_id = subprocess.check_output([git_binary, "rev-parse", "HEAD"], cwd=source_dir).decode('utf-8').strip()
  File "C:\depot_tools\win_tools-2_7_6_bin\python\bin\lib\subprocess.py", line 566, in check_output
    process = Popen(stdout=PIPE, *popenargs, **kwargs)
  File "C:\depot_tools\win_tools-2_7_6_bin\python\bin\lib\subprocess.py", line 709, in __init__
    errread, errwrite)
  File "C:\depot_tools\win_tools-2_7_6_bin\python\bin\lib\subprocess.py", line 957, in _execute_child
    startupinfo)
WindowsError: [Error 2] The system cannot find the file specified

Confirmation of Vulkan-LoaderAndValidationLayers bugfix commit currently awaiting merge over there as working solution for building Chromium.

https://github.com/KhronosGroup/Vulkan-LoaderAndValidationLayers/pull/2295/commits/73ffa98419f04a599eb7d7365f41613b7469f709

Assigning to jmadill

Let's roll back ANGLE. Jamie is not responding to my ping, so probably out on vacation already.

offending ANGLE CL is reverted: https://chromium-review.googlesource.com/c/angle/angle/+/842918

Now I am kicking another ANGLE roll

https://chromium-review.googlesource.com/c/chromium/src/+/843229

Since the revert is pending, reducing to P2 and blocking  issue angleproject:2237 

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7ffa24cf171dfee90f565cf3453557ece1069342

commit 7ffa24cf171dfee90f565cf3453557ece1069342
Author: Zhenyao Mo <zmo@chromium.org>
Date: Fri Dec 22 20:50:50 2017

Roll ANGLE 2b7bbc2..06f8637

https://chromium.googlesource.com/angle/angle.git/+log/2b7bbc2..06f8637

BUG= 797253 
TEST=bots
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.win:win_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel
TBR=jmadill@chromium.org,thestig@chromium.org

Change-Id: I85383d0eb6618c11b306d954d7c697a44a8a090d
Reviewed-on: https://chromium-review.googlesource.com/843229
Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Commit-Queue: Zhenyao Mo <zmo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#526057}
[modify] https://crrev.com/7ffa24cf171dfee90f565cf3453557ece1069342/DEPS

Do the Windows bots have git installed? I thought they get it from depot tools just like dev machines?

Here is the failure output:

[3391/25621] ACTION
//third_party/angle/src/vulkan_support...nal_revision_generate(//build/toolchain/win:win_clang_x86)
FAILED: gen/third_party/angle/src/vulkan_support/angle/vulkan/spirv_tools_commit_id.h
C:/python_27_amd64/files/python.exe
../../third_party/vulkan-validation-layers/src/scripts/external_revision_generator.py
../../third_party/spirv-tools-angle/src SPIRV_TOOLS_COMMIT_ID
gen/third_party/angle/src/vulkan_support/angle/vulkan/spirv_tools_commit_id.h
Traceback (most recent call last):
  File "../../third_party/vulkan-validation-layers/src/scripts/external_revision_generator.py",
line 38, in <module>
    commit_id = subprocess.check_output([git_binary, "rev-parse",
"HEAD"], cwd=source_dir).decode('utf-8').strip()
  File "C:\python_27_amd64\files\lib\subprocess.py", line 537, in check_output
    process = Popen(stdout=PIPE, *popenargs, **kwargs)
  File "C:\python_27_amd64\files\lib\subprocess.py", line 679, in __init__
    errread, errwrite)
  File "C:\python_27_amd64\files\lib\subprocess.py", line 896, in _execute_child
    startupinfo)
WindowsError: [Error 2] The system cannot find the file specified
[3590/25621] CC obj/third_party/brotli/brotli/static_dict.obj
ninja: build stopped: subcommand failed.

Thanks Mo for reverting this. Sorry for the mess up. Re-landing in https://chromium-review.googlesource.com/c/angle/angle/+/845859, thanks Kai for helping me test this locally without git installed.