Remove all uses of toolkit_use_gtk in the gyp files.

chrome/PRESUBMIT.py

 # Copyright (c) 2011 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.
 
 """Presubmit script for changes affecting chrome/
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into gcl.
 """
 
 import re
 
 INCLUDE_CPP_FILES_ONLY = (
   r'.*\.cc$', r'.*\.h$'
 )
 
 EXCLUDE = (
   # Objective C confuses everything.
   r'.*cocoa.*',
   r'.*_mac\.(cc|h)$',
   r'.*_mac_.*',
   # All the messages files do weird multiple include trickery
   r'.*_messages.*\.h$',
   r'render_messages.h$',
   # Autogenerated window resources files are off limits
   r'.*resource.h$',
-  # GTK macros in C-ish header code cause false positives
-  r'gtk_.*\.h$',
   # Header trickery
   r'.*-inl\.h$',
   # Templates
   r'sigslotrepeater\.h$',
   # GCC attribute trickery
   r'sel_main\.cc$',
   # Mozilla code
   r'mork_reader\.h$',
   r'mork_reader\.cc$',
   r'nss_decryptor_linux\.cc$',
@@ skipping 41 matching lines @@
 def CheckChangeOnUpload(input_api, output_api):
   results = []
   results.extend(_CommonChecks(input_api, output_api))
   results.extend(_CheckChangeLintsClean(input_api, output_api))
   return results
 
 def CheckChangeOnCommit(input_api, output_api):
   results = []
   results.extend(_CommonChecks(input_api, output_api))
   return results