Cleanup VS 2013/2015 confusion in toolchain script

The get-toolchain script still contained leftover goop for installing
the UCRT, even though that misguided plan was abandoned last year. This
change deletes that.

The get-toolchain script also confusingly used the vs2013_files
directory for anything that wasn't VS 2015. It doesn't technically make
any difference now that we use hashes for the toolchain directories, but
it was confusing when experimenting with VS 2017.

R=sebmarchand@chromium.org
BUG=683729

Change-Id: Ie0d3eccffe4796d4c5e23a28276acdd757e290d4
Reviewed-on: https://chromium-review.googlesource.com/453122Reviewed-by: Sébastien Marchand <sebmarchand@chromium.org>
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>

win_toolchain/get_toolchain_if_necessary.py

@@ -366,39 +366,6 @@ def RemoveUnusedToolchains(root):
       RemoveToolchain(root, toolchain[1], True)
 
 
-def GetInstallerName():
-  """Return the name of the Windows 10 Universal C Runtime installer for the
-  current platform, or None if installer is not needed or not applicable.
-  The registry has to be used instead of sys.getwindowsversion() because
-  Python 2.7 is only manifested as being compatible up to Windows 8, so the
-  version APIs helpfully return a maximum of 6.2 (Windows 8).
-  """
-  key_name = r'Software\Microsoft\Windows NT\CurrentVersion'
-  key = winreg.OpenKey(winreg.HKEY_LOCAL_MACHINE, key_name)
-  value, keytype = winreg.QueryValueEx(key, "CurrentVersion")
-  key.Close()
-  if keytype != winreg.REG_SZ:
-    raise Exception("Unexpected type in registry")
-  if value == '6.1':
-    # Windows 7 and Windows Server 2008 R2
-    return 'Windows6.1-KB2999226-x64.msu'
-  elif value == '6.2':
-    # Windows 8 and Windows Server 2012
-    return 'Windows8-RT-KB2999226-x64.msu'
-  elif value == '6.3':
-    # Windows 8.1, Windows Server 2012 R2, and Windows 10.
-    # The Windows 8.1 installer doesn't work on Windows 10, but it will never
-    # be used because the UCRT is always installed on Windows 10.
-    return 'Windows8.1-KB2999226-x64.msu'
-  else:
-    # Some future OS.
-    return None
-
-
-def InstallUniversalCRTIfNeeded(abs_target_dir):
-  return
-
-
 def EnableCrashDumpCollection():
   """Tell Windows Error Reporting to record crash dumps so that we can diagnose
   linker crashes and other toolchain failures. Documented at:
@@ -451,10 +418,10 @@ def main():
   # the downloader script is.
   os.chdir(os.path.normpath(os.path.join(BASEDIR)))
   toolchain_dir = '.'
-  if os.environ.get('GYP_MSVS_VERSION') == '2015':
-    target_dir = os.path.normpath(os.path.join(toolchain_dir, 'vs_files'))
-  else:
+  if os.environ.get('GYP_MSVS_VERSION') == '2013':
     target_dir = os.path.normpath(os.path.join(toolchain_dir, 'vs2013_files'))
+  else:
+    target_dir = os.path.normpath(os.path.join(toolchain_dir, 'vs_files'))
   if not os.path.isdir(target_dir):
     os.mkdir(target_dir)
   toolchain_target_dir = os.path.join(target_dir, desired_hash)
@@ -536,9 +503,6 @@ def main():
 
   EnableCrashDumpCollection()
 
-  if os.environ.get('GYP_MSVS_VERSION') == '2015':
-    InstallUniversalCRTIfNeeded(abs_toolchain_target_dir)
-
   RemoveUnusedToolchains(target_dir)
 
   return 0