Use XFixes to update the clipboard sequence number.

build/linux/system.gyp

 # 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.
 
 {
   'conditions': [
     ['sysroot!=""', {
       'variables': {
         'pkg-config': './pkg-config-wrapper "<(sysroot)"',
       },
@@ skipping 310 matching lines @@
               '<!@(<(pkg-config) --libs-only-L --libs-only-other xext)',
             ],
             'libraries': [
               '<!@(<(pkg-config) --libs-only-l xext)',
             ],
           },
         }],
       ],
     },
     {
+      'target_name': 'xfixes',
+      'type': 'none',
+      'conditions': [
+        ['_toolset=="target"', {
+          'direct_dependent_settings': {
+            'cflags': [
+              '<!@(<(pkg-config) --cflags xfixes)',
+            ],
+          },
+          'link_settings': {
+            'ldflags': [
+              '<!@(<(pkg-config) --libs-only-L --libs-only-other xfixes)',
+            ],
+            'libraries': [
+              '<!@(<(pkg-config) --libs-only-l xfixes)',
+            ],
+          },
+        }],
+      ],
+    },
+    {
       'target_name': 'libgcrypt',
       'type': 'none',
       'conditions': [
         ['_toolset=="target" and use_cups==1', {
           'direct_dependent_settings': {
             'cflags': [
               '<!@(libgcrypt-config --cflags)',
             ],
           },
           'link_settings': {
@@ skipping 258 matching lines @@
             ],
             'libraries': [
               '<!@(<(pkg-config) --libs-only-l wayland-client wayland-egl xkbcommon)',
             ],
           },
         }],
       ],
     },
   ],
 }