Fix flicker for Mobile data & Wi-Fi page

Both "Mobile data usage" & "Non-carrier data usage".

By,
1. Add header in onCreate() instead of onViewCreated()
2. Keep the space for Spinner, and preload initial cycles
3. Keep the space for 3 usage summaries

Bug: 191730864
Test: manual
Change-Id: I8c309c5f51ce6290383a2d10f75e41d0f207d61a

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

@@ -31,6 +31,8 @@ public class SpinnerPreference extends Preference implements CycleAdapter.Spinne
     private AdapterView.OnItemSelectedListener mListener;
     private Object mCurrentObject;
     private int mPosition;
+    private View mItemView;
+    private boolean mItemViewVisible = false;
 
     public SpinnerPreference(Context context, AttributeSet attrs) {
         super(context, attrs);
@@ -63,12 +65,24 @@ public class SpinnerPreference extends Preference implements CycleAdapter.Spinne
     @Override
     public void onBindViewHolder(PreferenceViewHolder holder) {
         super.onBindViewHolder(holder);
+        mItemView = holder.itemView;
+        mItemView.setVisibility(mItemViewVisible ? View.VISIBLE : View.INVISIBLE);
         Spinner spinner = (Spinner) holder.findViewById(R.id.cycles_spinner);
         spinner.setAdapter(mAdapter);
         spinner.setSelection(mPosition);
         spinner.setOnItemSelectedListener(mOnSelectedListener);
     }
 
+    void setHasCycles(boolean hasData) {
+        setVisible(hasData);
+        if (hasData) {
+            mItemViewVisible = true;
+            if (mItemView != null) {
+                mItemView.setVisibility(View.VISIBLE);
+            }
+        }
+    }
+
     @Override
     protected void performClick(View view) {
         view.findViewById(R.id.cycles_spinner).performClick();