AU: Optionally limit the size of delta update operations.

Add a --chunk_size flag to delta_generator. If it's not -1, files will
be split into chunks of this size when generating delta payloads. This
effectively limits the size of each delta operation.

BUG=chromium:229797
TEST=unit tests; generated delta payloads and checked them through
paycheck.py.

Change-Id: I21502118088bfbac75aa8009eb144f6aaf23a83a
Reviewed-on: https://gerrit.chromium.org/gerrit/48357
Commit-Queue: Darin Petkov <petkov@chromium.org>
Reviewed-by: Darin Petkov <petkov@chromium.org>
Tested-by: Darin Petkov <petkov@chromium.org>
diff --git a/graph_utils.cc b/graph_utils.cc
index 47d0c53..02b49c3 100644
--- a/graph_utils.cc
+++ b/graph_utils.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2009 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -155,9 +155,10 @@
         type_str = "REPLACE_BZ";
         break;
     }
-    LOG(INFO) << i 
+    LOG(INFO) << i
               << (graph[i].valid ? "" : "-INV")
               << ": " << graph[i].file_name
+              << " " << graph[i].chunk_size << "@" << graph[i].chunk_offset
               << ": " << type_str;
     LOG(INFO) << "  src_extents:";
     DumpExtents(graph[i].op.src_extents(), 4);