Revert of Change default Windows compiler to VS 2015 (patchset #1 id:1 of https://codereview.chromium.org/1740583002/ )

Reason for revert:
Broke isolate tests on Win8 GN (dbg) and Win x64 GN (dbg).
https://build.chromium.org/p/chromium.win/builders/Win8%20GN%20%28dbg%29/builds/22695/steps/isolate%20tests/logs/stdio

[found] [hashed/size/to hash] [looked up/to lookup] [uploaded/size/to upload/size]
04:10:31.512494 Root: E:\b\build\slave\Win8_GN__dbg_\build\src
04:10:31.513479 Root: E:\b\build\slave\Win8_GN__dbg_\build\src

events_unittests  GetFileAttributesEx E:\b\build\slave\Win8_GN__dbg_\build\src\out\Debug\msvcp120d.dll: The system cannot find the file specified.
04:10:31.988532 PushDirectory(E:\b\build\slave\Win8_GN__dbg_\build\src\content\test\data\) = 1574 files
04:10:32.060523 PushDirectory(E:\b\build\slave\Win8_GN__dbg_\build\src\media\test\data\) = 233 files
04:10:32.435549 PushDirectory(E:\b\build\slave\Win8_GN__dbg_\build\src\net\data\) = 974 files
04:10:32.464549 PushDirectory(E:\b\build\slave\Win8_GN__dbg_\build\src\net\tools\testserver\) = 11 files
[2843] [6/29.0Mib/39] [0/6] [0/0b/0/0b] 1s
04:10:32.505555 PushDirectory(E:\b\build\slave\Win8_GN__dbg_\build\src\third_party\pyftpdlib\) = 37 files
04:10:32.539557 PushDirectory(E:\b\build\slave\Win8_GN__dbg_\build\src\third_party\pywebsocket\) = 99 files
04:10:32.578571 PushDirectory(E:\b\build\slave\Win8_GN__dbg_\build\src\third_party\tlslite\) = 105 files

content_browsertests  GetFileAttributesEx E:\b\build\slave\Win8_GN__dbg_\build\src\out\Debug\msvcp120d.dll: The system cannot find the file specified.
Hits    :     0 (0b)
Misses  :     0 (0b)
Duration: 1.301s
isolate: GetFileAttributesEx E:\b\build\slave\Win8_GN__dbg_\build\src\out\Debug\msvcp120d.dll: The system cannot find the file specified.
step returned non-zero exit code: 1

Original issue's description:
> Reland of Change default Windows compiler to VS 2015
>
> The change to get_landmines.py is there because modifying this file
> affects analyze behavior so that all tests run. Changing the printed
> message is purely a side effect.
>
> This change also removes some redundant INCLUDE paths. These are
> unnecessary when building with VS 2015 (because it defaults to the
> Windows 10 SDK) and actively harmful (they make the INCLUDE path
> problematically long).
>
> This change was redone in order to fix merge conflicts and because after
> a few weeks a fresh set of approvals seems reasonable.
>
> The original change was landed as crrev.com/1598493004
>
> BUG=440500, 584782
>
> Committed: https://crrev.com/d4dcbd342dd54f55383daf8bc44b2c9d97fe0d0b
> Cr-Commit-Position: refs/heads/master@{#380382}

TBR=scottmg@chromium.org,dpranke@chromium.org,brucedawson@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=440500, 584782

Review URL: https://codereview.chromium.org/1778343002

Cr-Commit-Position: refs/heads/master@{#380395}

1 files changed, 3 insertions, 5 deletions

diff --git a/build/vs_toolchain.py b/build/vs_toolchain.py
index 1105ea7..66f4cc4 100755
--- a/build/vs_toolchain.py
+++ b/build/vs_toolchain.py
@@ -22,8 +22,8 @@ json_data_file = os.path.join(script_dir, 'win_toolchain.json')
 import gyp
 
 
-# Use MSVS2015 as the default toolchain.
-CURRENT_DEFAULT_TOOLCHAIN_VERSION = '2015'
+# Use MSVS2013 as the default toolchain.
+CURRENT_DEFAULT_TOOLCHAIN_VERSION = '2013'
 
 
 def SetEnvironmentAndGetRuntimeDllDirs():
@@ -281,6 +281,7 @@ def _GetDesiredVsToolchainHashes():
     # Update 1 with hot fixes.
     return ['391bbf1220d3edcd3cc3fccdb56224181e3b13a7']
   else:
+    # Default to VS2013.
     return ['4087e065abebdca6dbd0caca2910c6718d2ec67f']
 
 
@@ -314,9 +315,6 @@ def Update(force=False):
         depot_tools_win_toolchain):
     import find_depot_tools
     depot_tools_path = find_depot_tools.add_depot_tools_to_path()
-    # Necessary so that get_toolchain_if_necessary.py will put the VS toolkit
-    # in the correct directory.
-    os.environ['GYP_MSVS_VERSION'] = GetVisualStudioVersion()
     get_toolchain_args = [
         sys.executable,
         os.path.join(depot_tools_path,