Only force fastbuild=1 when use_goma if not already set

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 2292 matching lines @@
 
       ['desktop_linux==1 and use_aura==1 and use_x11==1', {
         'use_clipboard_aurax11%': 1,
       }],
 
       ['OS=="win" and use_goma==1', {
         # goma doesn't support pch yet.
         'chromium_win_pch': 0,
         # goma doesn't support PDB yet, so win_z7=1 or fastbuild=1.
         'conditions': [
-          ['win_z7==0', {
+          ['win_z7==0 and fastbuild==0', {
             'fastbuild': 1,
           }],
         ],
       }],
 
       ['OS=="win" and (clang==1 or asan==1)', {
         'chromium_win_pch': 0,
       }],
 
       ['host_clang==1', {
@@ skipping 3468 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',
   },
 }