Fix flaky TabListBackendTest

tools/telemetry/telemetry/core/backends/chrome/tab_list_backend_unittest.py

Index: tools/telemetry/telemetry/core/backends/chrome/tab_list_backend_unittest.py
diff --git a/tools/telemetry/telemetry/core/backends/chrome/tab_list_backend_unittest.py b/tools/telemetry/telemetry/core/backends/chrome/tab_list_backend_unittest.py
index c4377dbfa9aca5ebf9401769d63bd5a9b4509202..5ceacbbb139fdfc01af67b604b166d359b2930dc 100644
--- a/tools/telemetry/telemetry/core/backends/chrome/tab_list_backend_unittest.py
+++ b/tools/telemetry/telemetry/core/backends/chrome/tab_list_backend_unittest.py
@@ -1,11 +1,14 @@
 # Copyright 2015 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.
+
+from telemetry import decorators
 from telemetry.core import exceptions
 from telemetry.unittest_util import tab_test_case
 
 
 class TabListBackendTest(tab_test_case.TabTestCase):
+  @decorators.Enabled('has tabs')
   def testTabIdMatchesContextId(self):
     # Ensure that there are two tabs.
     while len(self.tabs) < 2:
@@ -18,6 +21,7 @@ class TabListBackendTest(tab_test_case.TabTestCase):
       self.assertEquals(tab.id, context_id)
       tabs.append(self.tabs.GetTabById(context_id))
 
+  @decorators.Enabled('has tabs')
   def testTabIdStableAfterTabCrash(self):
     # Ensure that there are two tabs.
     while len(self.tabs) < 2: