Telemetry: Clean up perf profiler unit tests.

tools/telemetry/telemetry/unittest/simple_mock.py

Index: tools/telemetry/telemetry/unittest/simple_mock.py
diff --git a/tools/telemetry/telemetry/unittest/simple_mock.py b/tools/telemetry/telemetry/unittest/simple_mock.py
index b54dcac7231ef6337be6861d6bfc5b7f5c77441e..6d22ffd106c2bc3f39d573d36a480e2065b659f8 100644
--- a/tools/telemetry/telemetry/unittest/simple_mock.py
+++ b/tools/telemetry/telemetry/unittest/simple_mock.py
@@ -66,6 +66,9 @@ class MockObject(object):
     assert isinstance(value, MockObject)
     object.__setattr__(self, name, value)
 
+  def SetAttribute(self, name, value):
+    setattr(self, name, value)
+
   def ExpectCall(self, func_name, *args):
     assert self._trace.next_call_index == 0
     if not hasattr(self, func_name):