Fixed Linux bots to disable GPU otherwise process is terminated

tools/testing/dart/test_suite.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Classes and methods for enumerating and preparing tests.
  *
  * This library includes:
  *
  * - Creating tests by listing all the Dart files in certain directories,
@@ skipping 1320 matching lines @@
       var fullHtmlPath =
           _getUriForBrowserTest(htmlPath_subtest, subtestName).toString();
 
       if (runtime == "drt") {
         var dartFlags = [];
         var contentShellOptions = [];
 
         contentShellOptions.add('--no-timeout');
         contentShellOptions.add('--dump-render-tree');
 
+        // Disable the GPU under Linux and Dartium. If the GPU is enabled,
+        // Chrome may send a termination signal to a test.  The test will be
+        // terminated if a machine (bot) doesn't have a GPU or if a test is
+        // still running after a certain period of time.
+        if (configuration['system'] == 'linux' &&
+            configuration['runtime'] == 'drt') {
+          contentShellOptions.add('--disable-gpu');
+        }
         if (compiler == 'none') {
           dartFlags.add('--ignore-unrecognized-flags');
           if (configuration["checked"]) {
             dartFlags.add('--enable_asserts');
             dartFlags.add("--enable_type_checks");
           }
           dartFlags.addAll(vmOptions);
         }
 
         commandSet.add(CommandBuilder.instance.getContentShellCommand(
@@ skipping 1103 matching lines @@
       for (var key in PATH_REPLACEMENTS.keys) {
         if (path.startsWith(key)) {
           path = path.replaceFirst(key, PATH_REPLACEMENTS[key]);
           break;
         }
       }
     }
     return path;
   }
 }