Add support for correct Windows 10 version enumeration.

base/win/windows_version.h

Index: base/win/windows_version.h
diff --git a/base/win/windows_version.h b/base/win/windows_version.h
index e51840b0db8bb2d8bf62d6a36a450fc0afff6eb1..4e2935082604f138d2498da8cc6829b6cb1cfa1c 100644
--- a/base/win/windows_version.h
+++ b/base/win/windows_version.h
@@ -27,6 +27,7 @@ enum Version {
   VERSION_WIN7,        // Also includes Windows Server 2008 R2.
   VERSION_WIN8,        // Also includes Windows Server 2012.
   VERSION_WIN8_1,      // Code named Windows Blue
+  VERSION_WIN10,       // Windows 10

[cpu_(ooo_6.6-7.5), 2015/01/31 22:02:03]

includes windows server 10? is so then say it.
and on that note windows server 2012 R2, where does it go?

[Will Harris, 2015/02/01 21:31:08]

Done.  Windows Server 2012 R2 reports as 6.3 which is same as Windows 8.1

Windows 10 Server (the SKU doesn't have an official name yet - some builds say
"vNext Server") also reports 10.0

   VERSION_WIN_LAST,    // Indicates error condition.
 };