firmware: start implementing close method

The close method is used to indicate something is done, for instance,
uploading a firmware image or tarball.

Change-Id: I9e972ea12282e700863d51db497c6294040cd2ca
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/static_handler.hpp b/static_handler.hpp
index edb3df5..0126315 100644
--- a/static_handler.hpp
+++ b/static_handler.hpp
@@ -20,7 +20,7 @@
         stagedFilename(temporaryName){};
 
     bool open(const std::string& path) override;
-
+    void close() override;
     bool write(std::uint32_t offset,
                const std::vector<std::uint8_t>& data) override;