shill: cellular: Consolidate singletons in CellularService

https://gerrit.chromium.org/gerrit/46485 consolidated singletons used in
cellular into ModemInfo.  Use a ModemInfo object in CellularService also
for the same function.

BUG=chromium:225038
TEST=unit-tests. Integration tests on try-bots. Test basic cellular
connection on link.

Change-Id: I0a13e8a746057ce0c8483be1c6fd5afd47bb59bb
Reviewed-on: https://gerrit.chromium.org/gerrit/47033
Commit-Queue: Prathmesh Prabhu <pprabhu@chromium.org>
Reviewed-by: Prathmesh Prabhu <pprabhu@chromium.org>
Tested-by: Prathmesh Prabhu <pprabhu@chromium.org>
diff --git a/cellular_capability_gsm_unittest.cc b/cellular_capability_gsm_unittest.cc
index 05fb184..3dd81e7 100644
--- a/cellular_capability_gsm_unittest.cc
+++ b/cellular_capability_gsm_unittest.cc
@@ -261,9 +261,7 @@
   }
 
   void SetService() {
-    cellular_->service_ = new CellularService(
-        modem_info_.control_interface(), modem_info_.dispatcher(),
-        modem_info_.metrics(), modem_info_.manager(), cellular_);
+    cellular_->service_ = new CellularService(&modem_info_, cellular_);
   }
 
   void SetupCommonProxiesExpectations() {