update_engine: Deprecate major version 1

We have moved away from major version 1 in Chrome OS and already have a
stepping stone for it in M53. So this cleanup makes the code much easier
to understand.

BUG=chromium:1008553
TEST=FEATURES="test" sudo emerge update_engine update_payload
TEST=cros_generate_update_payload --image chromiumos_test_image.bin --check --output delta.bin

Change-Id: I01815dfa5fdf395f8214ef162e01ecca2d42f7fc
Reviewed-on: https://chromium-review.googlesource.com/c/aosp/platform/system/update_engine/+/1857459
Tested-by: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Sen Jiang <senj@chromium.org>
Commit-Queue: Amin Hassani <ahassani@chromium.org>
diff --git a/payload_generator/payload_signer.h b/payload_generator/payload_signer.h
index 83ddadc..71f4983 100644
--- a/payload_generator/payload_signer.h
+++ b/payload_generator/payload_signer.h
@@ -39,12 +39,9 @@
   static bool VerifySignedPayload(const std::string& payload_path,
                                   const std::string& public_key_path);
 
-  // Adds specified signature offset/length to given |manifest|, also adds a
-  // dummy operation that points to a signature blob located at the specified
-  // offset/length if |add_dummy_op| is true.
+  // Adds specified signature offset/length to given |manifest|.
   static void AddSignatureToManifest(uint64_t signature_blob_offset,
                                      uint64_t signature_blob_length,
-                                     bool add_dummy_op,
                                      DeltaArchiveManifest* manifest);
 
   // Given a raw |hash| and a private key in |private_key_path| calculates the