Make timeline model able to return browser process

tools/telemetry/telemetry/core/timeline/thread.py

Index: tools/telemetry/telemetry/core/timeline/thread.py
diff --git a/tools/telemetry/telemetry/core/timeline/thread.py b/tools/telemetry/telemetry/core/timeline/thread.py
index 464a1c31ec3b4ec52e128c01702fe61a80ba7a22..9916d01c825183fbff445528b70377787544c83d 100644
--- a/tools/telemetry/telemetry/core/timeline/thread.py
+++ b/tools/telemetry/telemetry/core/timeline/thread.py
@@ -64,6 +64,11 @@ class Thread(event_container.TimelineEventContainer):
       for sub_slice in async_slice.IterEventsInThisContainerRecrusively():
         yield sub_slice
 
+  def IterAllAsyncSlicesOfName(self, name):
+    for s in self.IterAllAsyncSlices():
+      if s.name == name:
+        yield s
+
   def IterEventsInThisContainer(self):
     return itertools.chain(
       iter(self._newly_added_slices),