pid: add helper methods for thermal controller types

Add helper methods for thermal controller types, such as checking if a
string is a supported thermal type and which type that string
corresponds to.

Change-Id: I3c782f5825e7726f264dd186df583bde0a0dc861
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/pid/thermalcontroller.hpp b/pid/thermalcontroller.hpp
index 317219c..1a602a2 100644
--- a/pid/thermalcontroller.hpp
+++ b/pid/thermalcontroller.hpp
@@ -18,6 +18,22 @@
     absolute
 };
 
+/**
+ * Get the ThermalType for a given string.
+ *
+ * @param[in] typeString - a string representation of a type.
+ * @return the ThermalType representation.
+ */
+ThermalType getThermalType(const std::string& typeString);
+
+/**
+ * Is the type specified a thermal type?
+ *
+ * @param[in] typeString - a string representation of a PID type.
+ * @return true if it's a thermal PID type.
+ */
+bool isThermalType(const std::string& typeString);
+
 class ThermalController : public PIDController
 {
   public: