Fix summary text on A11y SUW hub screen and remove unused String.

Bug: 26966572

Change-Id: I31ab0a18b1e98564d1eead338fdbfa224dbded77

src/com/android/settings/accessibility/ToggleFontSizePreferenceFragment.java

@@ -30,7 +30,6 @@ import com.android.settings.R;
  * Preference fragment used to control font size.
  */
 public class ToggleFontSizePreferenceFragment extends PreviewSeekBarPreferenceFragment {
-    private static final String LOG_TAG = "ToggleFontSizePreferenceFragment";
 
     private float[] mValues;
 

src/com/android/settings/display/ScreenZoomPreference.java

@@ -20,6 +20,7 @@ import android.content.Context;
 import android.content.Intent;
 import android.support.v4.content.res.TypedArrayUtils;
 import android.support.v7.preference.PreferenceGroup;
+import android.text.TextUtils;
 import android.util.AttributeSet;
 
 /**
@@ -39,7 +40,7 @@ public class ScreenZoomPreference extends PreferenceGroup {
         if (defaultIndex < 0) {
             setVisible(false);
             setEnabled(false);
-        } else {
+        } else if (TextUtils.isEmpty(getSummary())) {
             final String[] entries = density.getEntries();
             final int currentIndex = density.getCurrentIndex();
             setSummary(entries[currentIndex]);