AU: delta compress the kernel partition

src/platform/update_engine/update_metadata.proto

Index: src/platform/update_engine/update_metadata.proto
diff --git a/src/platform/update_engine/update_metadata.proto b/src/platform/update_engine/update_metadata.proto
index 115d513cfc018c5c513dc9d724a2046313820611..2fa8392e9ce8112169f502c04c902a9e67383d73 100644
--- a/src/platform/update_engine/update_metadata.proto
+++ b/src/platform/update_engine/update_metadata.proto
@@ -90,10 +90,8 @@ message DeltaArchiveManifest {
     optional uint64 dst_length = 7;
   }
   repeated InstallOperation install_operations = 1;
-  // The checksums of the install device before and after the install process.
-  optional string src_checksum = 2;
-  optional string dst_checksum = 3;
+  repeated InstallOperation kernel_install_operations = 2;
 
   // (At time of writing) usually 4096
-  optional uint32 block_size = 5 [default = 4096];
+  optional uint32 block_size = 3 [default = 4096];
 }