sensors/zones: place in namespace and cleanup

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I527dbc8477a232945f696227a7b0b2adbee45175
diff --git a/test/pid_stepwisecontroller_unittest.cpp b/test/pid_stepwisecontroller_unittest.cpp
index f5f6f9a..d9a7728 100644
--- a/test/pid_stepwisecontroller_unittest.cpp
+++ b/test/pid_stepwisecontroller_unittest.cpp
@@ -9,6 +9,11 @@
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
 
+namespace pid_control
+{
+namespace
+{
+
 using ::testing::Return;
 using ::testing::StrEq;
 
@@ -83,3 +88,6 @@
         p->process();
     }
 }
+
+} // namespace
+} // namespace pid_control