sensors/zones: place in namespace and cleanup

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I527dbc8477a232945f696227a7b0b2adbee45175
diff --git a/test/sensor_mock.hpp b/test/sensor_mock.hpp
index b067c7c..d67c457 100644
--- a/test/sensor_mock.hpp
+++ b/test/sensor_mock.hpp
@@ -5,6 +5,9 @@
 
 #include <gmock/gmock.h>
 
+namespace pid_control
+{
+
 class SensorMock : public Sensor
 {
   public:
@@ -16,3 +19,5 @@
     MOCK_METHOD0(read, ReadReturn());
     MOCK_METHOD1(write, void(double));
 };
+
+} // namespace pid_control