Pass lsan GYP variable to swarming's test_env so that we can disable the sandbox when it's set.

chrome/interactive_ui_tests.isolate

 # Copyright 2013 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': [
     ['OS=="linux"', {
       'variables': {
         'command': [
           '../testing/xvfb.py',
           '<(PRODUCT_DIR)',
           '<(PRODUCT_DIR)/interactive_ui_tests<(EXECUTABLE_SUFFIX)',
           '--test-launcher-bot-mode',
+          '--lsan=<(lsan)',
         ],
         'isolate_dependency_tracked': [
           '../testing/xvfb.py',
           '<(PRODUCT_DIR)/libffmpegsumo.so',
           '<(PRODUCT_DIR)/libosmesa.so',
         ],
         'isolate_dependency_untracked': [
           '<(PRODUCT_DIR)/pyproto/',
         ],
       },
@@ skipping 88 matching lines @@
           '../google_apis/test/',
           '<(PRODUCT_DIR)/resources/chromeos/',
         ],
       },
     }],
   ],
   'includes': [
     '../base/base.isolate',
   ],
 }