Add OpenVR SDK to third_party

third_party/openvr/src/src/vrcommon/vrpathregistry_public.h

+//========= Copyright Valve Corporation ============//
+#pragma once
+
+#include <string>
+#include <vector>
+#include <stdint.h>
+
+static const char *k_pchRuntimeOverrideVar = "VR_OVERRIDE";
+static const char *k_pchConfigOverrideVar = "VR_CONFIG_PATH";
+static const char *k_pchLogOverrideVar = "VR_LOG_PATH";
+
+class CVRPathRegistry_Public
+{
+public:
+        static std::string GetVRPathRegistryFilename();
+        static std::string GetOpenVRConfigPath();
+
+public:
+        CVRPathRegistry_Public();
+
+        /** Returns paths using the path registry and the provided override values. Pass NULL for any paths you don't care about. 
+        * Returns false if the path registry could not be read. Valid paths might still be returned based on environment variables. */
+        static bool GetPaths( std::string *psRuntimePath, std::string *psConfigPath, std::string *psLogPath, const char *pchConfigPathOverride, const char *pchLogPathOverride, std::vector<std::string> *pvecExternalDrivers = NULL );
+
+        bool BLoadFromFile();
+        bool BSaveToFile() const;
+
+        bool ToJsonString( std::string &sJsonString );
+
+        // methods to get the current values
+        std::string GetRuntimePath() const;
+        std::string GetConfigPath() const;
+        std::string GetLogPath() const;
+
+protected:
+        typedef std::vector< std::string > StringVector_t;
+
+        // index 0 is the current setting
+        StringVector_t m_vecRuntimePath;
+        StringVector_t m_vecLogPath;
+        StringVector_t m_vecConfigPath;
+
+        // full list of external drivers
+        StringVector_t m_vecExternalDrivers;
+};