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
diff --git a/src/com/android/settings/SettingsPreferenceFragment.java b/src/com/android/settings/SettingsPreferenceFragment.java
index a8bd3092..a79045a 100644
--- a/src/com/android/settings/SettingsPreferenceFragment.java
+++ b/src/com/android/settings/SettingsPreferenceFragment.java
@@ -52,7 +52,7 @@
 /**
  * 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 {
 
     /**
@@ -133,10 +133,6 @@
     }
 
     @Override
-    public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
-    }
-
-    @Override
     public void addPreferencesFromResource(@XmlRes int preferencesResId) {
         super.addPreferencesFromResource(preferencesResId);
         checkAvailablePrefs(getPreferenceScreen());