Correct SignedEncryptionInfo.public_key_id.

The declaration in proto would now match code and TIN.

Bug: b:170054326
Change-Id: I1204ec91bf592ba31d592abb4461f9b83c81ae7d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2615102
Commit-Queue: Leonid Baraz <lbaraz@chromium.org>
Auto-Submit: Leonid Baraz <lbaraz@chromium.org>
Reviewed-by: Zach Trudo <zatrudo@google.com>
Cr-Commit-Position: refs/heads/master@{#841308}

chrome/browser/policy/messaging_layer/encryption/decryption.cc

@@ -152,8 +152,8 @@ void Decryptor::RecordKeyPair(
                        " actual=", base::NumberToString(public_key.size())}));
             } else {
               // Assign a random number to be public key id for testing purposes
-              // only (in production it will be Java Fingerprint2011 which is
-              // 'long').
+              // only (in production it will be retrieved from the server as
+              // 'int32').
               Encryptor::PublicKeyId public_key_id;
               base::RandBytes(&public_key_id, sizeof(public_key_id));
               if (!decryptor->keys_.emplace(public_key_id, key_info).second) {

components/policy/proto/record.proto

@@ -116,7 +116,8 @@ message SignedEncryptionInfo {
 
   // Public key id (required).
   // Identifies private key matching |public_asymmetric_key| for the server.
-  optional uint64 public_key_id = 2;
+  // Matches Encryptor::PublicKeyId.
+  optional int32 public_key_id = 2;
 
   // Signature of |public_asymmetric_key| (required).
   // Verified by client against a well-known signature.