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/modem_manager.h b/modem_manager.h
index 0f26910..8947798 100644
--- a/modem_manager.h
+++ b/modem_manager.h
@@ -22,6 +22,7 @@
 class ControlInterface;
 class EventDispatcher;
 class Manager;
+class Metrics;
 class Modem;
 class ModemManagerProxyInterface;
 class ProxyFactory;
@@ -33,6 +34,7 @@
                const std::string &path,
                ControlInterface *control_interface,
                EventDispatcher *dispatcher,
+               Metrics *metrics,
                Manager *manager,
                GLib *glib,
                mobile_provider_db *provider_db);
@@ -95,6 +97,7 @@
 
   ControlInterface *control_interface_;
   EventDispatcher *dispatcher_;
+  Metrics *metrics_;
   Manager *manager_;
   GLib *glib_;
   mobile_provider_db *provider_db_;