Use c:\goma\goma-win64 as default gomadir on Windows.

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 272 matching lines @@
           }],
 
           ['use_ozone==1', {
             'use_ozone_evdev%': 1,
           }, {
             'use_ozone_evdev%': 0,
           }],
 
           # Set default gomadir.
           ['OS=="win"', {
-            'gomadir': 'c:\\goma\\goma-win',
+            'gomadir': 'c:\\goma\\goma-win64',
           }, {
             'gomadir': '<!(/bin/echo -n ${HOME}/goma)',
           }],
 
           # Set the default "target_subarch" on iOS. Valid values are "arm32",
           # "arm64" and "both" (meaning a fat binary).
           ['OS=="ios"', {
             'target_subarch%': 'arm64',
           }],
 
@@ skipping 6049 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',
   },
 }