AU: Some graph types and a couple utility functions
These will be used by the delta diff generator.
Review URL: http://codereview.chromium.org/578009
diff --git a/graph_utils.h b/graph_utils.h
new file mode 100644
index 0000000..62ecfd5
--- /dev/null
+++ b/graph_utils.h
@@ -0,0 +1,31 @@
+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_GRAPH_UTILS_H__
+#define CHROMEOS_PLATFORM_UPDATE_ENGINE_GRAPH_UTILS_H__
+
+#include <vector>
+#include "base/basictypes.h"
+#include "update_engine/graph_types.h"
+#include "update_engine/update_metadata.pb.h"
+
+// A few utility functions for graphs
+
+namespace chromeos_update_engine {
+
+namespace graph_utils {
+
+// Returns the number of blocks represented by all extents in the edge.
+uint64 EdgeWeight(const Graph& graph, const Edge& edge);
+
+// block must either be the next block in the last extent or a block
+// in the next extent. This function will not handle inserting block
+// into an arbitrary place in the extents.
+void AppendBlockToExtents(std::vector<Extent>* extents, uint64 block);
+
+} // namespace graph_utils
+
+} // namespace chromeos_update_engine
+
+#endif // CHROMEOS_PLATFORM_UPDATE_ENGINE_GRAPH_UTILS_H__