handler: Implement read/write/close/delete

Implement read/write/close/delete as pass-through functions.

Signed-off-by: Kun Yi <kunyi@google.com>
Change-Id: I56b935b03b8048a70a168d00061c043795b90f5e
diff --git a/binarystore.hpp b/binarystore.hpp
index 0fc316b..11ca241 100644
--- a/binarystore.hpp
+++ b/binarystore.hpp
@@ -27,6 +27,7 @@
     virtual bool canHandleBlob(const std::string& blobId) const = 0;
     virtual bool openOrCreateBlob(const std::string& blobId,
                                   uint16_t flags) = 0;
+    virtual bool deleteBlob(const std::string& blobId) = 0;
     virtual std::vector<uint8_t> read(uint32_t offset,
                                       uint32_t requestedSize) = 0;
     virtual bool write(uint32_t offset, const std::vector<uint8_t>& data) = 0;