Set max num of slices allowed in panel view

Setup a max allowed num for PanelSlicesAdapter to prevent too
many slices showing in single panel.

Test: Manual verify
Test: atest PanelSlicesAdapterTest
Fixes: 129358092
Change-Id: I7b72a29489e597b8309d74841eaeab0fe42aace6

src/com/android/settings/panel/PanelSlicesAdapter.java

@@ -44,6 +44,12 @@ import java.util.List;
 public class PanelSlicesAdapter
         extends RecyclerView.Adapter<PanelSlicesAdapter.SliceRowViewHolder> {
 
+    /**
+     * Maximum number of slices allowed on the panel view.
+     */
+    @VisibleForTesting
+    static final int MAX_NUM_OF_SLICES = 5;
+
     private final List<LiveData<Slice>> mSliceLiveData;
     private final int mMetricsCategory;
     private final PanelFragment mPanelFragment;
@@ -70,14 +76,21 @@ public class PanelSlicesAdapter
         sliceRowViewHolder.onBind(mSliceLiveData.get(position));
     }
 
+    /**
+     * Return the number of available items in the adapter with max number of slices enforced.
+     */
     @Override
     public int getItemCount() {
-        return mSliceLiveData.size();
+        return Math.min(mSliceLiveData.size(), MAX_NUM_OF_SLICES);
     }
 
+    /**
+     * Return the available data from the adapter. If the number of Slices over the max number
+     * allowed, the list will only have the first MAX_NUM_OF_SLICES of slices.
+     */
     @VisibleForTesting
     List<LiveData<Slice>> getData() {
-        return mSliceLiveData;
+        return mSliceLiveData.subList(0, getItemCount());
     }
 
     /**