Clear power consumption auditing when you clear history.

components/power/origin_power_map.h

Index: components/power/origin_power_map.h
diff --git a/components/power/origin_power_map.h b/components/power/origin_power_map.h
index 36caa02f0ada89238b9bc3ae7270391f9cc13dc7..3d664daa4845a0d4031883a30d2e9f7d98598d94 100644
--- a/components/power/origin_power_map.h
+++ b/components/power/origin_power_map.h
@@ -43,6 +43,9 @@ class OriginPowerMap : public KeyedService {
   // updating for all origins this cycle.
   void OnAllOriginsUpdated();
 
+  // Clears all URLs out of the map.
+  void ClearOriginMap();
+
  private:
   // OriginMap maps a URL to the amount of power consumed by the URL using the
   // same units as |total_consumed_|.