Add DeviceSettingProvider unit tests.

chrome/browser/metrics/metrics_service.cc

 // Copyright (c) 2012 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.
 
 //------------------------------------------------------------------------------
 // Description of the life cycle of a instance of MetricsService.
 //
 //  OVERVIEW
 //
 // A MetricsService instance is typically created at application startup.  It
@@ skipping 384 matching lines @@
   DCHECK(IsSingleThreaded());
   InitializeMetricsState();
 
   base::Closure callback = base::Bind(&MetricsService::StartScheduledUpload,
                                       self_ptr_factory_.GetWeakPtr());
   scheduler_.reset(new MetricsReportingScheduler(callback));
   log_manager_.set_log_serializer(new MetricsLogSerializer());
   log_manager_.set_max_ongoing_log_store_size(kUploadLogAvoidRetransmitSize);
 }
 
+// Constrcutor for tests. Will not initialize the object for realz.
+MetricsService::MetricsService(bool active)
+    : recording_active_(active),
+      reporting_active_(active),
+      state_(INITIALIZED),
+      io_thread_(NULL),
+      idle_since_last_transmission_(false),
+      next_window_id_(0),
+      ALLOW_THIS_IN_INITIALIZER_LIST(self_ptr_factory_(this)),
+      ALLOW_THIS_IN_INITIALIZER_LIST(state_saver_factory_(this)),
+      waiting_for_asynchronus_reporting_step_(false) {
+  DCHECK(IsSingleThreaded());
+}
+
 MetricsService::~MetricsService() {
   SetRecording(false);
 }
 
 void MetricsService::Start() {
   HandleIdleSinceLastTransmission(false);
   SetRecording(true);
   SetReporting(true);
 }
 
@@ skipping 1251 matching lines @@
   if (local_state) {
     const PrefService::Preference* uma_pref =
         local_state->FindPreference(prefs::kMetricsReportingEnabled);
     if (uma_pref) {
       bool success = uma_pref->GetValue()->GetAsBoolean(&result);
       DCHECK(success);
     }
   }
   return result;
 }