win: Enable clang on Canary branch 2501.

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 1962 matching lines @@
             # Enable Keystone auto-update support.
             'mac_keystone%': 1,
           }, { # else: branding!="Chrome" or buildtype!="Official"
             'mac_breakpad_uploads%': 0,
             'mac_breakpad%': 0,
             'mac_keystone%': 0,
           }],
         ],
       }],  # OS=="mac" or OS=="ios"
       ['OS=="win"', {
+        'clang%': 1,
+
         'conditions': [
           # This is the architecture convention used in WinSDK paths.
           ['target_arch=="ia32"', {
             'winsdk_arch%': 'x86',
           },{
             'winsdk_arch%': '<(target_arch)',
           }],
           ['component=="shared_library" or MSVS_VERSION == "2015"', {
             # TODO(scottmg): The allocator shimming doesn't work on the 2015 CRT
             # and we are hoping to be able to remove it if an additional feature
@@ skipping 4340 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',
   },
 }