Use Clang's update.py --print-revision everywhere.

build/config/compiler/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/android/config.gni")
 import("//build/config/chrome_build.gni")
 if (current_cpu == "arm") {
   import("//build/config/arm.gni")
 }
 if (current_cpu == "mipsel" || current_cpu == "mips64el") {
@@ skipping 140 matching lines @@
     # Allow comparing the address of references and 'this' against 0
     # in debug builds. Technically, these can never be null in
     # well-defined C/C++ and Clang can optimize such checks away in
     # release builds, but they may be used in asserts in debug builds.
     cflags_cc += [
       "-Wno-undefined-bool-conversion",
       "-Wno-tautological-undefined-compare",
     ]
   }
 
-  if (is_clang && !is_win && !is_nacl) {
+  if (is_clang && !is_nacl) {
     # This is here so that all files get recompiled after a clang roll and
     # when turning clang on or off. (defines are passed via the command line,
     # and build system rebuild things when their commandline changes). Nothing
     # should ever read this define.
-    defines += [ "CR_CLANG_REVISION=" +
-                 exec_script("//tools/clang/scripts/posix-print-revision.py",
-                             [],
-                             "trim string") ]
+    defines +=
+        [ "CR_CLANG_REVISION=" + exec_script("//tools/clang/scripts/update.py",
+                                             [ "--print-revision" ],
+                                             "trim string") ]
   }
 
   # Mac-specific compiler flags setup.
   # ----------------------------------
   if (is_mac || is_ios) {
     # These flags are shared between the C compiler and linker.
     common_mac_flags = []
 
     # CPU architecture.
     if (current_cpu == "x64") {
@@ skipping 907 matching lines @@
       cflags += [ "-gsplit-dwarf" ]
     }
   }
 }
 
 config("no_symbols") {
   if (!is_win) {
     cflags = [ "-g0" ]
   }
 }