shill: Keeps track of successful wifi connection frequencies.

Saves the connection frequencies (and counts therefor) in the default
profile.  Sends number of frequencies on which successful connections
have been made to an UMA stat.

BUG=chromium:222081
TEST=unittests and manual (look for UMA stat
     'Network.Shill.Wifi.FrequenciesConnectedEver', disconnect from
     wifi, reconnect, verify that the UMA stat went up by 1).

Change-Id: I1e3c75b82ac387dd01066c4da4ebfce2c4b2ddc0
Reviewed-on: https://gerrit.chromium.org/gerrit/47154
Commit-Queue: Wade Guthrie <wdg@chromium.org>
Reviewed-by: Wade Guthrie <wdg@chromium.org>
Tested-by: Wade Guthrie <wdg@chromium.org>
diff --git a/profile.cc b/profile.cc
index 912a17c..6aa0406 100644
--- a/profile.cc
+++ b/profile.cc
@@ -301,6 +301,10 @@
   return false;
 }
 
+bool Profile::UpdateWiFiProvider(const WiFiProvider &wifi_provider) {
+  return false;
+}
+
 void Profile::HelpRegisterDerivedStrings(
     const string &name,
     Strings(Profile::*get)(Error *),