Linux: clean up the usage of "use_cups" gyp switch:

chrome/chrome_browser.gypi

 # 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.
 
 {
   'targets': [
     {
       'target_name': 'browser',
       'type': '<(library)',
       'msvs_guid': '5BF908A7-68FB-4A4B-99E3-8C749F1FE4EA',
@@ skipping 3464 matching lines @@
             'browser/first_run/upgrade_util.cc',
             'browser/first_run/upgrade_util.h',
             'browser/first_run/upgrade_util_linux.cc',
             'browser/password_manager/native_backend_gnome_x.cc',
             'browser/password_manager/native_backend_gnome_x.h',
             'browser/password_manager/native_backend_kwallet_x.cc',
             'browser/password_manager/native_backend_kwallet_x.h',
             'browser/platform_util_linux.cc',
           ],
         }],
+        ['use_cups==1', {
+          'dependencies': [
+            '../printing/printing.gyp:cups',
+          ],
+        }],
         ['use_gconf==0', {
           'sources!': [
             'browser/ui/gtk/gconf_titlebar_listener.cc',
             'browser/ui/gtk/gconf_titlebar_listener.h',
           ],
         }],
         ['use_gnome_keyring==0', {
           'sources!': [
             'browser/password_manager/native_backend_gnome_x.cc',
             'browser/password_manager/native_backend_gnome_x.h',
@@ skipping 968 matching lines @@
       'hard_dependency': 1,
     },
   ],
 }
 
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 # tab-width:2
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