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

tools/telemetry/telemetry/timeline/model.py

Index: tools/telemetry/telemetry/timeline/model.py
diff --git a/tools/telemetry/telemetry/timeline/model.py b/tools/telemetry/telemetry/timeline/model.py
index c4d4bff2d0ce46d75f8709aa27a4bc01ae4accda..6c9c9e20a9ac27cb1c9769b34b025ac69ff10a56 100644
--- a/tools/telemetry/telemetry/timeline/model.py
+++ b/tools/telemetry/telemetry/timeline/model.py
@@ -1,11 +1,11 @@
 # 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.
-'''A container for timeline-based events and traces and can handle importing
+"""A container for timeline-based events and traces and can handle importing
 raw event data from different sources. This model closely resembles that in the
 trace_viewer project:
 https://code.google.com/p/trace-viewer/
-'''
+"""
 
 from operator import attrgetter
 
@@ -270,4 +270,4 @@ class TimelineModel(event_container.TimelineEventContainer):
 
       importers.sort(key=lambda k: k.import_order)
 
-    return importers
+    return importers