Rename ActionExitCode to ErrorCode

Nowadays ActionExitCode is used throughout the codebase so use a more
generic name to reflect this.

BUG=chromium:216507
TEST=unit tests pass

Change-Id: I23d1d7e2676443251dbc42ed137fd018aadfa8a3
Reviewed-on: https://gerrit.chromium.org/gerrit/49512
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Commit-Queue: David Zeuthen <zeuthen@chromium.org>
Tested-by: David Zeuthen <zeuthen@chromium.org>
diff --git a/payload_signer.cc b/payload_signer.cc
index 26d63db..86114b2 100644
--- a/payload_signer.cc
+++ b/payload_signer.cc
@@ -164,7 +164,7 @@
   // Loads the payload and parses the manifest.
   TEST_AND_RETURN_FALSE(utils::ReadFile(payload_path, &payload));
   LOG(INFO) << "Payload size: " << payload.size();
-  ActionExitCode error = kActionCodeSuccess;
+  ErrorCode error = kErrorCodeSuccess;
   InstallPlan install_plan;
   DeltaPerformer delta_performer(NULL, NULL, &install_plan);
   TEST_AND_RETURN_FALSE(delta_performer.ParsePayloadMetadata(