shill: Only complete cellular Start() early if proxies are initialized

BUG=chromium:371156
TEST=Unit tests, network_3GModemControl

Change-Id: I0176555226cf8802ef427f146109b1c373d52cb3
Reviewed-on: https://chromium-review.googlesource.com/210114
Reviewed-by: Ben Chan <benchan@chromium.org>
Commit-Queue: Thieu Le <thieule@chromium.org>
Tested-by: Thieu Le <thieule@chromium.org>
diff --git a/cellular_capability_cdma.cc b/cellular_capability_cdma.cc
index d07b785..9c937fc 100644
--- a/cellular_capability_cdma.cc
+++ b/cellular_capability_cdma.cc
@@ -88,6 +88,10 @@
   proxy_.reset();
 }
 
+bool CellularCapabilityCDMA::AreProxiesInitialized() const {
+  return (CellularCapabilityClassic::AreProxiesInitialized() && proxy_.get());
+}
+
 bool CellularCapabilityCDMA::AllowRoaming() {
   return allow_roaming_property();
 }