trace_processor: Fix behaviour of displayTimeUnit to match catapult

Bug: 205521938
Bug: https://github.com/google/perfetto/issues/141
Change-Id: I1c9abe192ed3cc1ce0ea285371af81c0d83549cc
diff --git a/CHANGELOG b/CHANGELOG
index 3bf07a9..dabf6bf 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -11,6 +11,7 @@
     * Changed LIKE comparisions to be case-senstive. This may break existing
       queries but was a necessary from a performance perspective.
     * Changed compiler flags, assume recent x64 CPUs (see above).
+    * Changed how displayTimeUnit is handled in JSON traces to match catapult.
   UI:
     *
   SDK: