Merge InstrumentedFragment & InstrumentedPerferenceFragment

Bug: 30642749

The 2 classes are almost identical so I'd like to just merge them if
there is no specific reason for keeping both.

Change-Id: I46af41388e25abf79066ff25bfb793cdef2e06ea

src/com/android/settings/SettingsPreferenceFragment.java

@@ -52,7 +52,7 @@ import java.util.UUID;
 /**
  * Base class for Settings fragments, with some helper functions and dialog management.
  */
-public abstract class SettingsPreferenceFragment extends InstrumentedPreferenceFragment
+public abstract class SettingsPreferenceFragment extends InstrumentedFragment
         implements DialogCreatable {
 
     /**
@@ -132,10 +132,6 @@ public abstract class SettingsPreferenceFragment extends InstrumentedPreferenceF
         return root;
     }
 
-    @Override
-    public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
-    }
-
     @Override
     public void addPreferencesFromResource(@XmlRes int preferencesResId) {
         super.addPreferencesFromResource(preferencesResId);