shill: cellular: Add Network.Shill.Cellular.DropsPerHour.

BUG=chromium-os:38557
TEST=Unit tests, manually lose LTE signal and check chrome://histograms

Change-Id: I82aa1edabd21c5dfde4834cd36a34a12b629ba8f
Reviewed-on: https://gerrit.chromium.org/gerrit/42813
Reviewed-by: Arman Uguray <armansito@chromium.org>
Commit-Queue: Thieu Le <thieule@chromium.org>
Tested-by: Thieu Le <thieule@chromium.org>
diff --git a/manager_unittest.cc b/manager_unittest.cc
index 74c0983..0c8b981 100644
--- a/manager_unittest.cc
+++ b/manager_unittest.cc
@@ -1904,7 +1904,7 @@
 }
 
 TEST_F(ManagerTest, SortServicesWithConnection) {
-  MockMetrics mock_metrics;
+  MockMetrics mock_metrics(dispatcher());
   SetMetrics(&mock_metrics);
 
   scoped_refptr<MockService> mock_service0(
@@ -1983,7 +1983,7 @@
   EXPECT_EQ(0, manager()->default_service_callback_tag_);
   EXPECT_TRUE(manager()->default_service_callbacks_.empty());
 
-  MockMetrics mock_metrics;
+  MockMetrics mock_metrics(dispatcher());
   SetMetrics(&mock_metrics);
 
   scoped_refptr<MockService> mock_service(
@@ -2627,7 +2627,7 @@
   EXPECT_FALSE(manager()->IsOnline());
   EXPECT_EQ("offline", manager()->CalculateState(NULL));
 
-  MockMetrics mock_metrics;
+  MockMetrics mock_metrics(dispatcher());
   SetMetrics(&mock_metrics);
   EXPECT_CALL(mock_metrics, NotifyDefaultServiceChanged(_))
       .Times(AnyNumber());
@@ -2659,7 +2659,7 @@
 }
 
 TEST_F(ManagerTest, CalculateStateOnline) {
-  MockMetrics mock_metrics;
+  MockMetrics mock_metrics(dispatcher());
   SetMetrics(&mock_metrics);
   EXPECT_CALL(mock_metrics, NotifyDefaultServiceChanged(_))
       .Times(AnyNumber());