[Telemetry] Add capability for values to reference external files.

tools/perf/measurements/smoothness_controller.py

Index: tools/perf/measurements/smoothness_controller.py
diff --git a/tools/perf/measurements/smoothness_controller.py b/tools/perf/measurements/smoothness_controller.py
index 8d3e07a184042f9f7676ea805e4c24327f2e0115..10441a6bc0cd6fe1ba5659e9418ed393e7585db7 100644
--- a/tools/perf/measurements/smoothness_controller.py
+++ b/tools/perf/measurements/smoothness_controller.py
@@ -11,6 +11,7 @@ from telemetry.page import page_test
 from telemetry.page.actions import action_runner
 from telemetry.value import list_of_scalar_values
 from telemetry.value import scalar
+from telemetry.value import trace
 from telemetry.web_perf import timeline_interaction_record as tir_module
 from telemetry.web_perf.metrics import smoothness
 
@@ -69,7 +70,8 @@ class SmoothnessController(object):
     # Add results of smoothness metric. This computes the smoothness metric for
     # the time ranges of gestures, if there is at least one, else the the time
     # ranges from the first action to the last action.
-
+    results.AddValue(trace.TraceValue(
+        results.current_page, 'trace', self._tracing_timeline_data))
     renderer_thread = self._timeline_model.GetRendererThreadFromTabId(
         tab.id)
     run_smooth_actions_record = None