Revert "Reland "New toolchain for Windows 10 19041 SDK""

This reverts commit 424526a0.

Reason for revert: win64-chrome build succeeded (progress) but
win32-chrome builder failed with a previously unseen error, shown
here:

[170/58214] ACTION //remoting/host/win:remoting_lib_idl_idl_action(//build/toolchain/win:win_clang_x86)
FAILED: gen/remoting/host/win/chromoting_lib.h gen/remoting/host/win/chromoting_lib.dlldata.c gen/remoting/host/win/chromoting_lib_i.c gen/remoting/host/win/chromoting_lib_p.c gen/remoting/host/win/chromoting_lib.tlb 
c:\b\s\w\ir\cipd_bin_packages\cpython\bin\python.exe ../../build/toolchain/win/midl.py environment.x86 c:/b/s/w/ir/cache/builder/src/third_party/win_build_output/midl/remoting/host/win gen/remoting/host/win 7219b935-4873-533b-9ce1-20c9e9b12def chromoting_lib.tlb chromoting_lib.h chromoting_lib.dlldata.c chromoting_lib_i.c chromoting_lib_p.c gen/remoting/host/win/chromoting_lib.idl /char signed /env win32 /Oicf
cl : Command line error D8027 : cannot execute 'c:\b\s\w\ir\cache\builder\src\third_party\depot_tools\win_toolchain\vs_files\a687d8e2e4114d9015eb550e1b156af21381faac\win_sdk\bin\..\..\VC\Tools\MSVC\14.26.28801\bin\HostX64\x86\c1.dll'
midl : command line error MIDL1003 : error returned by the C preprocessor (2)

Original change's description:
> Reland "New toolchain for Windows 10 19041 SDK"
> 
> This is a reland of 4a4f53a7
> 
> The original patch would fail to build on the mksnapshot step on
> Windows 7 (and server equivalents). This was due to two APISet DLLs
> that are required for the new dbghelp.dll. This change copies the two
> of them during gn gen. In order to have them as part of the isolates
> for cdb and in order to avoid dangerous ambiguity they are now
> required, which means that when this change lands the new SDK will be
> required. This is slightly disruptive for developers who aren't using
> our toolchain, but it seems unavoidable.
> 
> Developers who don't have the latest SDK installed will hit this error
> message during gn gen:
> 
>  Exception: api-ms-win-downlevel-kernel32-l2-1-0.dll not found in "..."
>  You must install the "Debugging Tools for Windows" feature from the
>  Windows 10 SDK, the 10.0.19041.0 version.
> 
> Original change's description:
> > New toolchain for Windows 10 19041 SDK
> >
> > This change updates the toolchain package used to build Chromium with
> > the 10.0.19041.0 (2020-04) SDK and VS 16.6.1. The d3dcompiler_47.dll
> > DLLs for x86 and x64 were swapped out for the 10.0.17134 versions (as
> > usual).
> >
> > The Debuggers directory was not swapped out this time because the
> > problem with loading dbghelp.dll on Windows 7
> > (https://crbug.com/1021650) has been resolved.
> >
> > The output for the cdb copy step was updated because one additional UCRT
> > DLL is now copied.
> >
> > Packaging was done on a Windows Server 2019 VM, cleanly created for this
> > purpose.
> >
> > The package was created by downloading the VS Professional 2019
> > installer from https://visualstudio.microsoft.com/downloads/
> > (free trial, not preview) and then running the installer like this:
> >
> > $ PATH_TO_INSTALLER.EXE ^
> >     --add Microsoft.VisualStudio.Workload.NativeDesktop ^
> >     --add Microsoft.VisualStudio.Component.VC.ATLMFC ^
> >     --add Microsoft.VisualStudio.Component.VC.Tools.ARM64 ^
> >     --add Microsoft.VisualStudio.Component.VC.MFC.ARM64 ^
> >     --includeRecommended --passive
> >
> > Then the latest Windows 10 SDK was downloaded and installed from
> > https://developer.microsoft.com/en-us/windows/downloads/windows-10-sdk/
> >
> > Then the packaging script was run like this:
> >
> >   python3 depot_tools\win_toolchain\package_from_installed.py 2019 -w 10.0.19041.0
> >
> > Since the new d3dcompiler_47.dll uses the UCRT and we want to avoid
> > shipping that (https://crbug.com/920704) the final packaging step was to
> > unzip the package, copy over the two copies of that DLL from the
> > previous toolchain's win_sdk\Redist, and then repackage the toolchain
> > with:
> >   > python3 package_from_installed.py --repackage=<full-path-to-toolchain-dir>
> >
> > UWP and ARM64 support and Python 3 compatibility were previously added
> > to package_from_installed.py.
> >
> > Future changes will require the new SDK, but for now the previous SDK
> > can also be used to build Chromium.
> >
> > The failures on the win*msvc* bots are unrelated. This was proven by
> > creating crrev.com/c/2245914 which is a NOP toolchain test. The existing
> > toolchain was repackaged with a single text file added and that caused
> > identical failures.
> >
> > Bug: 920704, 1014701, 10216507, 1089996
> > Change-Id: Ie496354582458aa8c1292ed4ef63d949ee2eb15d
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2225224
> > Commit-Queue: Bruce Dawson <brucedawson@chromium.org>
> > Reviewed-by: Henrik Andreasson <henrika@chromium.org>
> > Reviewed-by: Jamie Madill <jmadill@chromium.org>
> > Reviewed-by: Nico Weber <thakis@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#778924}
> 
> Bug: 920704, 1014701, 10216507, 1089996, 1095767
> Change-Id: I75e7653d57964e2929106e41b3f50594d3969e5f
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2249394
> Reviewed-by: Daniel Cheng <dcheng@chromium.org>
> Reviewed-by: Jesse McKenna <jessemckenna@google.com>
> Reviewed-by: Jamie Madill <jmadill@chromium.org>
> Commit-Queue: Bruce Dawson <brucedawson@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#780431}

TBR=dcheng@chromium.org,henrika@webrtc.org,thakis@chromium.org,brucedawson@chromium.org,henrika@chromium.org,jessemckenna@google.com,jmadill@chromium.org

Change-Id: If00e3865e66d9071189b2aca28f7541ecbdc6486
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 920704, 1014701, 10216507, 1089996, 1095767
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2255558Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#780467}

build/vs_toolchain.py

@@ -408,9 +408,7 @@ def _CopyDebugger(target_dir, target_cpu):
 
   # List of debug files that should be copied, the first element of the tuple is
   # the name of the file and the second indicates if it's optional.
-  debug_files = [('dbghelp.dll', False), ('dbgcore.dll', True),
-                 ('api-ms-win-downlevel-kernel32-l2-1-0.dll', False),
-                 ('api-ms-win-eventing-provider-l1-1-0.dll', False)]
+  debug_files = [('dbghelp.dll', False), ('dbgcore.dll', True)]
   for debug_file, is_optional in debug_files:
     full_path = os.path.join(win_sdk_dir, 'Debuggers', target_cpu, debug_file)
     if not os.path.exists(full_path):
@@ -420,7 +418,7 @@ def _CopyDebugger(target_dir, target_cpu):
         # TODO(crbug.com/773476): remove version requirement.
         raise Exception('%s not found in "%s"\r\nYou must install the '
                         '"Debugging Tools for Windows" feature from the Windows'
-                        ' 10 SDK, the 10.0.19041.0 version.'
+                        ' 10 SDK.'
                         % (debug_file, full_path))
     target_path = os.path.join(target_dir, debug_file)
     _CopyRuntimeImpl(target_path, full_path)
@@ -440,11 +438,12 @@ def _GetDesiredVsToolchainHashes():
   * //docs/windows_build_instructions.md mentions of VS or Windows SDK.
     Keeps the document consistent with the toolchain version.
   """
-  # VS 2019 16.61 with 10.0.19041 SDK, and 10.0.17134 version of
-  # d3dcompiler_47.dll, with ARM64 libraries and UWP support.
+  # VS 2019 Update 9 (16.3.29324.140) with 10.0.18362 SDK, 10.0.17763 version of
+  # Debuggers, and 10.0.17134 version of d3dcompiler_47.dll, with ARM64
+  # libraries and UWP support.
   # See go/chromium-msvc-toolchain for instructions about how to update the
   # toolchain.
-  toolchain_hash = 'a687d8e2e4114d9015eb550e1b156af21381faac'
+  toolchain_hash = '9ff60e43ba91947baca460d0ca3b1b980c3a2c23'
   # Third parties that do not have access to the canonical toolchain can map
   # canonical toolchain version to their own toolchain versions.
   toolchain_hash_mapping_key = 'GYP_MSVS_HASH_%s' % toolchain_hash

build/win/BUILD.gn

@@ -79,7 +79,6 @@ if (is_win) {
         "$root_out_dir/cdb/api-ms-win-crt-string-l1-1-0.dll",
         "$root_out_dir/cdb/api-ms-win-crt-time-l1-1-0.dll",
         "$root_out_dir/cdb/api-ms-win-crt-utility-l1-1-0.dll",
-        "$root_out_dir/cdb/api-ms-win-downlevel-kernel32-l2-1-0.dll",
         "$root_out_dir/cdb/api-ms-win-eventing-provider-l1-1-0.dll",
         "$root_out_dir/cdb/ucrtbase.dll",
       ]
@@ -163,8 +162,6 @@ if (is_win) {
           "$root_out_dir/api-ms-win-crt-string-l1-1-0.dll",
           "$root_out_dir/api-ms-win-crt-time-l1-1-0.dll",
           "$root_out_dir/api-ms-win-crt-utility-l1-1-0.dll",
-          "$root_out_dir/api-ms-win-downlevel-kernel32-l2-1-0.dll",
-          "$root_out_dir/api-ms-win-eventing-provider-l1-1-0.dll",
         ]
         if (!is_debug) {
           data += [ "$root_out_dir/ucrtbase.dll" ]