Reland [telemetry] Timeline model cleanups

tools/telemetry/telemetry/core/timeline/async_slice.py

Index: tools/telemetry/telemetry/core/timeline/async_slice.py
diff --git a/tools/telemetry/telemetry/core/timeline/tracing/async_slice.py b/tools/telemetry/telemetry/core/timeline/async_slice.py
similarity index 54%
rename from tools/telemetry/telemetry/core/timeline/tracing/async_slice.py
rename to tools/telemetry/telemetry/core/timeline/async_slice.py
index 03031c1e6e43bb5afdcd66c5444f37086507a965..140eadc651b7893e16c64b71b993b16b8e3e0514 100644
--- a/tools/telemetry/telemetry/core/timeline/tracing/async_slice.py
+++ b/tools/telemetry/telemetry/core/timeline/async_slice.py
@@ -2,20 +2,27 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import telemetry.core.timeline.tracing.slice as tracing_slice
+import telemetry.core.timeline.event as event
 
-class AsyncSlice(tracing_slice.Slice):
+class AsyncSlice(event.TimelineEvent):
   ''' A AsyncSlice represents an interval of time during which an
   asynchronous operation is in progress. An AsyncSlice consumes no CPU time
   itself and so is only associated with Threads at its start and end point.
   '''
-  def __init__(self, category, name, timestamp, args=None, parent=None):
+  def __init__(self, category, name, timestamp, args=None):
     super(AsyncSlice, self).__init__(
-        category, name, timestamp, args=args, parent=parent)
+        category, name, timestamp, duration=0, args=args)
+    self.parent_slice = None
     self.start_thread = None
     self.end_thread = None
+    self.sub_slices = []
     self.id = None
 
   def AddSubSlice(self, sub_slice):
-    super(AsyncSlice, self).AddSubSlice(sub_slice)
-    self.children.append(sub_slice)
+    assert sub_slice.parent_slice == self
+    self.sub_slices.append(sub_slice)
+
+
+  def IterEventsInThisContainerRecrusively(self):
+    for sub_slice in self.sub_slices:
+      yield sub_slice