Upgrade to Windows 10.0.18362.0 SDK (1903)

This updates Chrome to build with a toolchain based on VS 2017 15.9.12
and the Windows 10.0.18362.0 SDK. This package contains the 17134 version
of d3dcompiler_47.dll, to avoid gaining a dependency on the universal CRT
which would cause problems for some Windows 7 machines (bug 919163).

Packaging was done on a Windows Server 2019 VM, cleanly created for this
purpose.

The package was created by downloading VS 2017 Update 9.3, from
https://visualstudio.microsoft.com/vs/older-downloads and downloading
the 15.9 Visual Studio Professional 2017, 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 10.0.18362.0 SDK was installed from:
https://developer.microsoft.com/en-US/windows/downloads/windows-10-sdk

Then the packaging script was run like this:

  python depot_tools\win_toolchain\package_from_installed.py 2017 -w 10.0.18362.0

Since the new d3dcompiler_47.dll uses the UCRT and we want to avoid shipping
that the final packaging step was to unzip the package, copy over the two copies
of that DLL from win_sdk\Redist, and then repackage the toolchain with:
  > python package_from_installed.py --repackage=<full-path-to-toolchain-dir>

This is needed to make progress towards two-phase lookup.

Bug: 970064
Change-Id: Ib502b34f3281cb062eafff93e6d1054a968d4e9f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1650599
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#668944}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 3d2afd961cfc48a219c4b35ee3b2b6e554584e95

vs_toolchain.py

@@ -419,9 +419,9 @@ def _GetDesiredVsToolchainHashes():
   to build with."""
   env_version = GetVisualStudioVersion()
   if env_version == '2017':
-    # VS 2017 Update 9 (15.9.3) with 10.0.17763.132 SDK, 10.0.17134 version of
+    # VS 2017 Update 9 (15.9.12) with 10.0.18362.0 SDK, 10.0.17134 version of
     # d3dcompiler_47.dll, with ARM64 libraries.
-    toolchain_hash = '818a152b3f1da991c1725d85be19a0f27af6bab4'
+    toolchain_hash = 'b83892920cc15ef223a1b81cc64d98e1197d3678'
     # 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