Telemetry: Initialize smoothness and thread_times metrics before page load, not after.

tools/perf/measurements/smoothness.py

Index: tools/perf/measurements/smoothness.py
diff --git a/tools/perf/measurements/smoothness.py b/tools/perf/measurements/smoothness.py
index d771917a7613051a1ee462a4f5ad7817e7a83df4..932a01a52430ab41b03da677cb441aa7534d84bc 100644
--- a/tools/perf/measurements/smoothness.py
+++ b/tools/perf/measurements/smoothness.py
@@ -22,10 +22,13 @@ class Smoothness(page_measurement.PageMeasurement):
   def WillStartBrowser(self, browser):
     self._power_metric = power.PowerMetric(browser)
 
-  def WillRunActions(self, page, tab):
+  def WillNavigateToPage(self, page, tab):
     self._power_metric.Start(page, tab)
     self._smoothness_controller = smoothness_controller.SmoothnessController()
-    self._smoothness_controller.Start(page, tab)
+    self._smoothness_controller.SetUp(page, tab)
+
+  def WillRunActions(self, page, tab):
+    self._smoothness_controller.Start(tab)
 
   def DidRunActions(self, page, tab):
     self._power_metric.Stop(page, tab)