shill: Move Metrics from singleton to Shill daemon

While implementing chromium-os:24810, it was discovered that Metrics is
cleaner if it is passed around like ControlInterface, Dispatcher,
Manager, etc.  This approach also makes Metrics more testable.

BUG=chromium-os:24810
TEST=Unit tests, network_WiFiManager suite

Change-Id: I556a1bd11f21f0b93ecfeaae8855dfb99ed5e5f9
Reviewed-on: https://gerrit.chromium.org/gerrit/14099
Commit-Ready: Thieu Le <thieule@chromium.org>
Reviewed-by: Thieu Le <thieule@chromium.org>
Tested-by: Thieu Le <thieule@chromium.org>
diff --git a/metrics.h b/metrics.h
index 28208aa..1df9e5d 100644
--- a/metrics.h
+++ b/metrics.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+// Copyright (c) 2012 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.
 
@@ -116,11 +116,9 @@
   static const int kTimerHistogramMinMilliseconds;
   static const int kTimerHistogramNumBuckets;
 
+  Metrics();
   virtual ~Metrics();
 
-  // This is a singleton -- use Metrics::GetInstance()->Foo()
-  static Metrics *GetInstance();
-
   // Converts the WiFi frequency into the associated UMA channel enumerator.
   static WiFiChannel WiFiFrequencyToChannel(uint16 frequency);
 
@@ -209,8 +207,6 @@
   static const uint16 kWiFiFrequency5745;
   static const uint16 kWiFiFrequency5825;
 
-  Metrics();
-
   void InitializeCommonServiceMetrics(const Service *service);
   void UpdateServiceStateTransitionMetrics(ServiceMetrics *service_metrics,
                                            Service::ConnectState new_state);