Use a different algorithm with the low entropy source for field trials.

third_party/mt19937ar/mt19937ar.gyp

Index: third_party/mt19937ar/mt19937ar.gyp
===================================================================
--- third_party/mt19937ar/mt19937ar.gyp	(revision 0)
+++ third_party/mt19937ar/mt19937ar.gyp	(revision 0)
@@ -0,0 +1,19 @@
+# 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.
+
+{
+  'targets': [
+    {
+      'target_name': 'mt19937ar',
+      'type': 'static_library',
+      'sources': [
+        'mt19937ar.cc',
+        'mt19937ar.h',
+      ],
+      'include_dirs': [
+        '../..',
+      ],
+    },
+  ],
+}