Convey the value of the --host_javabase startup option to the server.

--
PiperOrigin-RevId: 149282686
MOS_MIGRATED_REVID=149282686
diff --git a/src/main/cpp/startup_options.h b/src/main/cpp/startup_options.h
index 7bde6e7..a931ab9 100644
--- a/src/main/cpp/startup_options.h
+++ b/src/main/cpp/startup_options.h
@@ -195,6 +195,10 @@
   // the --host_javabase option.
   std::string GetHostJavabase();
 
+  // Returns the explicit value of the --host_javabase startup option or the
+  // empty string if it was not specified on the command line.
+  std::string GetExplicitHostJavabase() const;
+
   // Port for gRPC command server. 0 means let the kernel choose, -1 means no
   // gRPC command server.
   int command_port;
@@ -230,6 +234,7 @@
 
  private:
   std::string host_javabase;
+  std::string default_host_javabase;
 };
 
 }  // namespace blaze