Standardize usage of virtual/override/final specifiers.

content/child/power_monitor_broadcast_source_unittest.cc

Index: content/child/power_monitor_broadcast_source_unittest.cc
diff --git a/content/child/power_monitor_broadcast_source_unittest.cc b/content/child/power_monitor_broadcast_source_unittest.cc
index 4e4694353722d0a015a5090e454e618b28482772..030e1353365ffd3b9ae95c8aa41c26124f7839f1 100644
--- a/content/child/power_monitor_broadcast_source_unittest.cc
+++ b/content/child/power_monitor_broadcast_source_unittest.cc
@@ -18,7 +18,7 @@ class PowerMonitorBroadcastSourceTest : public testing::Test {
     power_monitor_.reset(new base::PowerMonitor(
         scoped_ptr<base::PowerMonitorSource>(power_monitor_source_)));
   }
-  virtual ~PowerMonitorBroadcastSourceTest() {}
+  ~PowerMonitorBroadcastSourceTest() override {}
 
   PowerMonitorBroadcastSource* source() { return power_monitor_source_; }
   base::PowerMonitor* monitor() { return power_monitor_.get(); }