Log time between network drops -- from online to offline.

src/platform/metrics/power_states.h

+// Copyright (c) 2010 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.
+
+// A table of power states, to be included when building tabular things.
+//
+// This file is used to construct two things: an enumerated type in
+// metrics_daemon.h, and a table of structures with state names in
+// metrics_daemon.cc.  Including this file ensures that the two tables are
+// always in sync (and saves typing).  I don't know of other ways of achieving
+// the same result in C/C++, but it doesn't mean there isn't one.
+
+// Before you include this file, define STATE to do something useful, or else
+// if will be a no-op.  STATE will be undefined on exit.  Don't worry about
+// collisions for the STATE macro (as long as it's a macro) because the
+// compiler will flag them---in that case, just change the name.  If someone is
+// misguided enough to use STATE for something other than a macro, the error
+// messages will be slightly more complicated.
+
+
+#ifndef STATE
+#define STATE(name, capname)
+#endif
+
+STATE(on, On)
+STATE(mem, Mem)
+
+#undef STATE