tools: blob add writeMeta to interface

Add the blob write metadata command to the interface.  The LPC interface
will use write meta to configure the BMC's window.

Change-Id: I0266e62174fac428bf0fb84fb9d128451b69e4d8
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/tools/blob_interface.hpp b/tools/blob_interface.hpp
index 00031b8..07525c9 100644
--- a/tools/blob_interface.hpp
+++ b/tools/blob_interface.hpp
@@ -22,6 +22,17 @@
     virtual ~BlobInterface() = default;
 
     /**
+     * Write metadata to a blob.
+     *
+     * @param[in] session - the session id.
+     * @param[in] offset - the offset for the metadata to write.
+     * @param[in] bytes - the bytes to send.
+     * @throws BlobException on failure.
+     */
+    virtual void writeMeta(std::uint16_t session, std::uint32_t offset,
+                           const std::vector<std::uint8_t>& bytes) = 0;
+
+    /**
      * Write bytes to a blob.
      *
      * @param[in] session - the session id.