[Telemetry] Style fix, make docstrings consistent with style guide.

tools/telemetry/telemetry/timeline/trace_event_importer_unittest.py

Index: tools/telemetry/telemetry/timeline/trace_event_importer_unittest.py
diff --git a/tools/telemetry/telemetry/timeline/trace_event_importer_unittest.py b/tools/telemetry/telemetry/timeline/trace_event_importer_unittest.py
index e57bd203c104593a9391c0adf19992cf08562098..e8a3d3633aaaaf0e1558e093b4f342ab371948b0 100644
--- a/tools/telemetry/telemetry/timeline/trace_event_importer_unittest.py
+++ b/tools/telemetry/telemetry/timeline/trace_event_importer_unittest.py
@@ -693,11 +693,11 @@ class TraceEventTimelineImporterTest(unittest.TestCase):
     self.assertEqual(4, slice_event.args['z'])
 
   def testSliceHierarchy(self):
-    ''' The slice hierarchy should look something like this:
+    """The slice hierarchy should look something like this:
            [            a            ]
               [      b      ]  [ d ]
               [ c ]     [ e ]
-    '''
+    """
     events = [
       {'name': 'a', 'args': {}, 'pid': 52, 'ts': 100, 'cat': 'foo',
        'tid': 53, 'ph': 'B'},
@@ -1018,4 +1018,4 @@ class TraceEventTimelineImporterTest(unittest.TestCase):
 
     trace_data = trace_data_module.TraceData(events)
     m = timeline_model.TimelineModel(trace_data)
-    self.assertEqual(0, len(m.flow_events))
+    self.assertEqual(0, len(m.flow_events))