Revert "Revert "New protocol for property_service""

This reverts commit 70c4ecf2b562ec643c270d65e0585fe8506d064c.
Bug: http://b/33926793
Bug: http://b/34670529
Test: run bionic-unit-tests --gtest_filter=prop*

Change-Id: I75b28146805ff37fbdcf0543ccb515ee5895eb2a
diff --git a/init/property_service.h b/init/property_service.h
index e3a2acb..5d59473 100644
--- a/init/property_service.h
+++ b/init/property_service.h
@@ -27,14 +27,14 @@
     const char* name;
 };
 
-extern void property_init(void);
-extern void property_load_boot_defaults(void);
-extern void load_persist_props(void);
-extern void load_system_props(void);
-extern void start_property_service(void);
+void property_init(void);
+void property_load_boot_defaults(void);
+void load_persist_props(void);
+void load_system_props(void);
+void start_property_service(void);
 std::string property_get(const char* name);
-extern int property_set(const char *name, const char *value);
-extern bool is_legal_property_name(const std::string &name);
+uint32_t property_set(const std::string& name, const std::string& value);
+bool is_legal_property_name(const std::string& name);
 
 
 #endif  /* _INIT_PROPERTY_H */