If a public key is present, disallow old style full payloads.

This is necessary to ensure that if a public key is present the payload is
signed and the signature passes verification.

BUG=chromium-os:11760
TEST=unit tests, tested on device

Change-Id: I6af61ead0e918c0b971dbcfeabcab3be03e6eb97

Review URL: http://codereview.chromium.org/6574009
diff --git a/action_processor.h b/action_processor.h
index 124fe00..ef06181 100644
--- a/action_processor.h
+++ b/action_processor.h
@@ -40,6 +40,7 @@
   kActionCodeDownloadWriteError = 14,
   kActionCodeNewRootfsVerificationError = 15,
   kActionCodeNewKernelVerificationError = 16,
+  kActionCodeSignedDeltaPayloadExpectedError = 17,
   kActionCodeOmahaRequestEmptyResponseError = 200,
   kActionCodeOmahaRequestXMLParseError = 201,
   kActionCodeOmahaRequestNoUpdateCheckNode = 202,