re-enable unittest related to TracingControllerBackend on CrOS

BUG=412713

Review URL: https://codereview.chromium.org/1029323002

Cr-Commit-Position: refs/heads/master@{#322006}

tools/telemetry/telemetry/core/backends/chrome_inspector/tracing_backend_unittest.py

@@ -77,7 +77,6 @@ class TracingBackendTest(tab_test_case.TabTestCase):
       self.skipTest('Browser does not support tracing, skipping test.')
     self._StartServer()
 
-  @decorators.Disabled('chromeos') # crbug.com/412713.
   def testGotTrace(self):
     options = tracing_options.TracingOptions()
     options.enable_chrome_trace = True
@@ -89,7 +88,6 @@ class TracingBackendTest(tab_test_case.TabTestCase):
     model = model_module.TimelineModel(trace_data)
     assert len(model.processes) > 0
 
-  @decorators.Disabled('chromeos') # crbug.com/412713.
   def testStartAndStopTraceMultipleTimes(self):
     options = tracing_options.TracingOptions()
     options.enable_chrome_trace = True

tools/telemetry/telemetry/core/browser_unittest.py

@@ -107,7 +107,6 @@ class BrowserTest(browser_test_case.BrowserTestCase):
   def testGetSystemTotalMemory(self):
     self.assertTrue(self._browser.memory_stats['SystemTotalPhysicalMemory'] > 0)
 
-  @decorators.Disabled('chromeos') # crbug.com/412713.
   def testIsTracingRunning(self):
     tracing_controller = self._browser.platform.tracing_controller
     if not tracing_controller.IsChromeTracingSupported():

tools/telemetry/telemetry/core/tab_unittest.py

@@ -97,7 +97,6 @@ class TabTest(tab_test_case.TabTestCase):
       self._tab.browser._platform_backend = original_platform_backend
 
   # Test failing on android: http://crbug.com/437057
-  # Also for chromeos: http://crbug.com/412713
   # and mac: http://crbug.com/468675
   @decorators.Disabled('android', 'chromeos', 'mac')
   def testHighlight(self):
@@ -120,7 +119,6 @@ class TabTest(tab_test_case.TabTestCase):
     self.assertTrue(found_video_start_event)
 
   @decorators.Enabled('has tabs')
-  @decorators.Disabled('chromeos') # crbug.com/412713.
   def testGetRendererThreadFromTabId(self):
     self.assertEquals(self._tab.url, 'about:blank')
     # Create 3 tabs. The third tab is closed before we call