shill: Retrieve cellular signal strength in capability delegates.

Refactor only, no functional changes.

BUG=chromium-os:18735
TEST=unit tests

Change-Id: I71e5dce70fcb018a156229799a8e2e1c2bfa8e89
Reviewed-on: https://gerrit.chromium.org/gerrit/11480
Reviewed-by: Darin Petkov <petkov@chromium.org>
Tested-by: Darin Petkov <petkov@chromium.org>
Commit-Ready: Darin Petkov <petkov@chromium.org>
diff --git a/cellular_capability_gsm.cc b/cellular_capability_gsm.cc
index 4fa1f5c..5954a98 100644
--- a/cellular_capability_gsm.cc
+++ b/cellular_capability_gsm.cc
@@ -61,6 +61,13 @@
   }
 }
 
+void CellularCapabilityGSM::GetSignalQuality() {
+  VLOG(2) << __func__;
+  // TODO(petkov): Switch to asynchronous calls (crosbug.com/17583).
+  uint32 strength = cellular()->modem_gsm_network_proxy()->GetSignalQuality();
+  cellular()->HandleNewSignalQuality(strength);
+}
+
 void CellularCapabilityGSM::RequirePIN(
     const string &pin, bool require, Error */*error*/) {
   VLOG(2) << __func__ << "(" << pin << ", " << require << ")";