shill: Clean up protected fields

...as per style.  I did omit property_store_unittest.h, which I'll
assign to cmasone instead of closing the issue.

BUG=chromium-os:19573
TEST=Rerun unit tests

Change-Id: I37874b6e71f50e91ca753d1ef4f1e25abf77032d
Reviewed-on: http://gerrit.chromium.org/gerrit/6764
Reviewed-by: Paul Stewart <pstew@chromium.org>
Tested-by: Paul Stewart <pstew@chromium.org>
Reviewed-by: Darin Petkov <petkov@chromium.org>
diff --git a/ipconfig.h b/ipconfig.h
index db0bc17..08a7c19 100644
--- a/ipconfig.h
+++ b/ipconfig.h
@@ -92,8 +92,6 @@
   // to its associated device.
   std::string GetStorageIdentifier(const std::string &id_suffix);
 
-  PropertyStore store_;
-
  private:
   friend class IPConfigAdaptorInterface;
   friend class ConnectionTest;
@@ -110,6 +108,7 @@
   static const char kType[];
   static uint global_serial_;
 
+  PropertyStore store_;
   const std::string device_name_;
   const std::string type_;
   const uint serial_;