scheduler: Put unit test code in anonymous namespace.

components/download/internal/scheduler/battery_listener_unittest.cc

Index: components/download/internal/scheduler/battery_listener_unittest.cc
diff --git a/components/download/internal/scheduler/battery_listener_unittest.cc b/components/download/internal/scheduler/battery_listener_unittest.cc
index 02a87afde1e83b33d27883b636d3ffb42c633740..3ddacffbf1060046f8fb6192885af8cd17c467d8 100644
--- a/components/download/internal/scheduler/battery_listener_unittest.cc
+++ b/components/download/internal/scheduler/battery_listener_unittest.cc
@@ -11,6 +11,7 @@
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace download {
+namespace {
 
 using BatteryRequirements = SchedulingParams::BatteryRequirements;
 
@@ -69,4 +70,5 @@ TEST_F(BatteryListenerTest, NotifyObservers) {
   listener_->Stop();
 };
 
+}  // namespace
 }  // namespace download