Add quotes to CR_CLANG_REVISION define

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")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/nacl/config.gni")
 import("//build/toolchain/cc_wrapper.gni")
 import("//build/toolchain/toolchain.gni")
@@ skipping 237 matching lines @@
       "-Wno-undefined-bool-conversion",
       "-Wno-tautological-undefined-compare",
     ]
   }
 
   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=$clang_revision" ]
+    defines += [ "CR_CLANG_REVISION=\"$clang_revision\"" ]
   }
 
   # Non-Mac Posix compiler flags setup.
   # -----------------------------------
   if (is_posix && !(is_mac || is_ios)) {
     if (enable_profiling) {
       if (!is_debug) {
         cflags += [ "-g" ]
 
         if (enable_full_stack_frames_for_profiling) {
@@ skipping 1425 matching lines @@
 
 if (is_ios || is_mac) {
   # On Mac and iOS, this enables support for ARC (automatic ref-counting).
   # See http://clang.llvm.org/docs/AutomaticReferenceCounting.html.
   config("enable_arc") {
     common_flags = [ "-fobjc-arc" ]
     cflags_objc = common_flags
     cflags_objcc = common_flags
   }
 }