clang/win: Make diagnostics colored if ansicon is around at runhooks time.

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 112 matching lines @@
       }
 
       if (current_cpu == "x86") {
         cflags += [
           "/fallback",
           "-m32",
         ]
       } else {
         cflags += [ "-m64" ]
       }
+      if (exec_script("//build/win/use_ansi_codes.py", [], "trim string") ==
+          "True") {
+        cflags += [
+          # cmd.exe doesn't understand ANSI escape codes by default,
+          # so only enable them if something emulating them is around.
+          "-fansi-escape-codes",
+        ]
+      }
     }
   } else {
     # Common GCC compiler flags setup.
     # --------------------------------
     cflags += [ "-fno-strict-aliasing" ]  # See http://crbug.com/32204
     cflags_cc += [
       "-fno-threadsafe-statics",
 
       # Not exporting C++ inline functions can generally be applied anywhere
       # so we do so here. Normal function visibility is controlled by
@@ skipping 1113 matching lines @@
       cflags += [ "-gsplit-dwarf" ]
     }
   }
 }
 
 config("no_symbols") {
   if (!is_win) {
     cflags = [ "-g0" ]
   }
 }