AU: Split applied update verification into a separate step.

Use instances of FilesystemCopierAction to do applied update verification. This
speeds it up slightly because asynchronous reads happen in parallel with hash
calculation but, more importantly, makes update_engine be responsive to D-Bus
during that step.

BUG=9140
TEST=unit tests, tested on device

Change-Id: I3ec9445de5e8258a63433a61f1a476aef4434f6c

Review URL: http://codereview.chromium.org/5516009
diff --git a/action_processor.h b/action_processor.h
index 8bd890b..0cf6ff6 100644
--- a/action_processor.h
+++ b/action_processor.h
@@ -36,8 +36,10 @@
   kActionCodeDownloadHashMismatchError = 10,
   kActionCodeDownloadSizeMismatchError = 11,
   kActionCodeDownloadPayloadVerificationError = 12,
-  kActionCodeDownloadAppliedUpdateVerificationError = 13,
+  kActionCodeDownloadNewPartitionInfoError = 13,
   kActionCodeDownloadWriteError = 14,
+  kActionCodeNewRootfsVerificationError = 15,
+  kActionCodeNewKernelVerificationError = 16,
   kActionCodeOmahaRequestEmptyResponseError = 200,
   kActionCodeOmahaRequestXMLParseError = 201,
   kActionCodeOmahaRequestNoUpdateCheckNode = 202,