shill: Delete existing routes when the device is started.

BUG=chromium-os:27358
TEST=Unit tests, network_WiFiManager, manually add foreign routes and
ensure they are deleted, also test to make sure default route remains
after DHCP renewal

Change-Id: Ic26b70d685491f31699ff4684ed289e76af8a9ca
Reviewed-on: https://gerrit.chromium.org/gerrit/17640
Commit-Ready: Thieu Le <thieule@chromium.org>
Reviewed-by: Thieu Le <thieule@chromium.org>
Tested-by: Thieu Le <thieule@chromium.org>
diff --git a/mock_routing_table.h b/mock_routing_table.h
index 55cf583..ec65029 100644
--- a/mock_routing_table.h
+++ b/mock_routing_table.h
@@ -27,7 +27,7 @@
   MOCK_METHOD3(SetDefaultRoute, bool(int interface_index,
                                      const IPConfigRefPtr &ipconfig,
                                      uint32 metric));
-  MOCK_METHOD2(FlushRoutes, void(int interface_index, bool all_routes));
+  MOCK_METHOD1(FlushRoutes, void(int interface_index));
   MOCK_METHOD0(FlushCache, bool());
   MOCK_METHOD1(ResetTable, void(int interface_index));
   MOCK_METHOD2(SetDefaultMetric, void(int interface_index, uint32 metric));