Log visibility change for all fragments.

Bug: 30681771
Test: SettingsUnitTests

Refactor visibility logging from InstrumentedFragment into a mixin. And
apply mixin in remaining fragments.

Change-Id: Ibbb59904336254a3e4bb9e8c7d0b36e5a6bc2622

src/com/android/settings/datausage/DataUsageList.java

@@ -109,7 +109,7 @@ public class DataUsageList extends DataUsageBase {
     private View mHeader;
 
     @Override
-    protected int getMetricsCategory() {
+    public int getMetricsCategory() {
         return MetricsEvent.DATA_USAGE_LIST;
     }