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

build/common.gypi

 # Copyright (c) 2012 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 5754 matching lines @@
                 ],
               },
             }],
             ['clang==1 and MSVS_VERSION == "2015"', {
               'VCCLCompilerTool': {
                 'AdditionalOptions': [
                   '-fmsc-version=1900',
                 ],
               },
             }],
+            ['clang==1 and "<!(python <(DEPTH)/build/win/use_ansi_codes.py)"=="True"', {
+              'VCCLCompilerTool': {
+                'AdditionalOptions': [
+                  # cmd.exe doesn't understand ANSI escape codes by default,
+                  # so only enable them if something emulating them is around.
+                  '-fansi-escape-codes',
+                  # Also see http://crbug.com/110262
+                  '-fcolor-diagnostics',
+                ],
+              },
+            }],
           ],
         },
       },
     }],
     ['disable_nacl==1', {
       'target_defaults': {
         'defines': [
           'DISABLE_NACL',
         ],
       },
@@ skipping 413 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }