Add protobuf definitions

Add protobuf definitions for binaryblob store, and change data types
to the generated class.

Signed-off-by: Kun Yi <kunyi@google.com>
Change-Id: I856a000c4a81c10bbbd1983d51712b4999a4e29e
diff --git a/proto/binaryblob.proto b/proto/binaryblob.proto
new file mode 100644
index 0000000..ceb7735
--- /dev/null
+++ b/proto/binaryblob.proto
@@ -0,0 +1,15 @@
+syntax = "proto2";
+
+package binstore.binaryblobproto;
+
+message BinaryBlob {
+    optional string blob_id = 1; // A valid, unique unix path as identifier
+    optional bytes data = 2;
+}
+
+/* BinaryBlobBase is analogous to a directory of BinaryBlobs. */
+message BinaryBlobBase {
+    optional string blob_base_id = 1; // Common parent path of contained blobs
+    repeated BinaryBlob blobs = 2;
+    optional uint32 max_size_bytes = 3;
+}