Enable some profile_chrome unit tests on Trybots

systrace/profile_chrome/chrome_tracing_agent_unittest.py

 # Copyright 2014 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.
 
 import json
 
 from profile_chrome import chrome_tracing_agent
 from profile_chrome import agents_unittest
+from systrace import decorators
 
 
 class ChromeAgentTest(agents_unittest.BaseAgentTest):
+  # TODO: This test seems to fail on the version of Android currently on the
+  # Trybot servers (KTU84P), although it works on Android M. Either upgrade the
+  # version of Android on the Trybot servers or determine if there is a way to
+  # run this agent on Android KTU84P.
+  @decorators.Disabled
   def testGetCategories(self):
     categories = \
         chrome_tracing_agent.ChromeTracingAgent.GetCategories(
             self.device, self.package_info)
 
     self.assertEquals(len(categories), 2)
     self.assertTrue(categories[0])
     self.assertTrue(categories[1])
 
+  @decorators.ClientOnlyTest
   def testTracing(self):
     categories = '*'
     ring_buffer = False
     agent = chrome_tracing_agent.ChromeTracingAgent(self.device,
                                                     self.package_info,
                                                     ring_buffer)
 
     agent.StartAgentTracing(chrome_tracing_agent.ChromeConfig(categories, None,
                                                               None, None, None,
                                                               None, None,
                                                               None))
     agent.StopAgentTracing()
     result = agent.GetResults()
     json.loads(result.raw_data)