Enable SwiftShader fallback on desktop Linux.

chrome/tools/build/linux/FILES.cfg

 # -*- python -*-
 # ex: set syntax=python:
 
 # 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.
 
 # This is a buildbot configuration file containing a tagged list of files
 # processed by the stage/archive scripts. The known tags are:
 #
@@ skipping 106 matching lines @@
   },
   # ANGLE files:
   {
     'filename': 'libGLESv2.so',
     'buildtype': ['dev'],
   },
   {
     'filename': 'libEGL.so',
     'buildtype': ['dev'],
   },
+  # SwiftShader files:
+  {
+    'filename': 'swiftshader/libGLESv2.so',
+    'buildtype': ['dev, 'official''],
+  },
+  {
+    'filename': 'swiftshader/libEGL.so',
+    'buildtype': ['dev', 'official'],
+  },
   # Native Client plugin files:
   {
     'filename': 'nacl_irt_x86_32.nexe',
     'arch': ['32bit'],
     'buildtype': ['dev', 'official'],
   },
   {
     'filename': 'nacl_irt_x86_64.nexe',
     'arch': ['64bit'],
     'buildtype': ['dev', 'official'],
@@ skipping 136 matching lines @@
     'archive': 'content-shell.zip',
     'optional': ['dev'],
   },
   {
     'filename': 'resources',
     'buildtype': ['dev'],
     'archive': 'content-shell.zip',
     'optional': ['dev'],
   },
  ]