Add basic daily active use logging.

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.
+// See network_states.h for details.
 
 
 #ifndef STATE
 #define STATE(name, capname)
 #endif
 
 STATE(on, On)
 STATE(mem, Mem)
 
 #undef STATE