shill: Set Device.Scanning property to |false| after timeout.

In the presence of low (no) network signal, modems sometimes remain in
the SEARCHING state indefinitely, which prevents the UI from getting
updated properly. Shill now sets the Device.Scanning property to |false|
after a 60 second timeout, if the modem hasn't registered with a
cellular network.

BUG=chromium-os:38807
TEST=1. Build and run unittests.
     2. Go to a low (zero) coverage area and enable cellular connectivity
        (either disable/enable through the UI or shut down and start the
        device).
     3. The UI should show the "Initializing..." message.
     4. After 60 seconds, the UI should update to a "No network..."
        message.
     5. Disable/enable device, but this time move to an area with good
        coverage.
     6. If everything else works correctly, the UI should no longer show
        the "Initializing..." message and display the correct cellular
        network.

Change-Id: I8f0f896a92187fc1ba515c47abbd68d7d65c01e6
Reviewed-on: https://gerrit.chromium.org/gerrit/43079
Commit-Queue: Arman Uguray <armansito@chromium.org>
Reviewed-by: Arman Uguray <armansito@chromium.org>
Tested-by: Arman Uguray <armansito@chromium.org>
diff --git a/cellular_operator_info.h b/cellular_operator_info.h
index 85acd73..21bd6cf 100644
--- a/cellular_operator_info.h
+++ b/cellular_operator_info.h
@@ -74,7 +74,7 @@
     friend class CellularCapabilityUniversalTest;
     friend class CellularOperatorInfo;
     friend class CellularOperatorInfoTest;
-    FRIEND_TEST(CellularCapabilityUniversalTest, UpdateStorageIdentifier);
+    FRIEND_TEST(CellularCapabilityUniversalMainTest, UpdateStorageIdentifier);
     FRIEND_TEST(CellularOperatorInfoTest, HandleMCCMNC);
     FRIEND_TEST(CellularOperatorInfoTest, HandleSID);