shill: Replace VLOG with SLOG.

This CL replaces all uses of VLOG(level) with SLOG(scope, level) with
the same verbose level and an appropriate scope for each affected
logging statement.

BUG=chromium-os:29641
TEST=Build and run unit tests. Test scope logging with ff_debug.

Change-Id: Ifdcf1faa2a309bcbd9ee369a66179ce9c7f1ad19
Reviewed-on: https://gerrit.chromium.org/gerrit/20629
Commit-Ready: Ben Chan <benchan@chromium.org>
Reviewed-by: Ben Chan <benchan@chromium.org>
Tested-by: Ben Chan <benchan@chromium.org>
diff --git a/wifi_endpoint.cc b/wifi_endpoint.cc
index dbe2c32..e7450a8 100644
--- a/wifi_endpoint.cc
+++ b/wifi_endpoint.cc
@@ -13,6 +13,7 @@
 
 #include "shill/ieee80211.h"
 #include "shill/proxy_factory.h"
+#include "shill/scope_logger.h"
 #include "shill/supplicant_bss_proxy_interface.h"
 #include "shill/wifi.h"
 #include "shill/wifi_endpoint.h"
@@ -80,8 +81,8 @@
       properties.find(wpa_supplicant::kBSSPropertySignal);
   if (properties_it != properties.end()) {
     signal_strength_ = properties_it->second.reader().get_int16();
-    VLOG(2) << "WiFiEndpoint " << bssid_string_ << " signal is now "
-            << signal_strength_;
+    SLOG(WiFi, 2) << "WiFiEndpoint " << bssid_string_ << " signal is now "
+                  << signal_strength_;
     device_->NotifyEndpointChanged(*this);
   }
 }