Unify NewTabPageItem and ItemGroup into a single tree-structured interface.

chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/CardViewHolder.java

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.ntp.cards;
 
 import android.support.annotation.CallSuper;
 import android.support.annotation.DrawableRes;
 import android.support.v4.view.animation.FastOutSlowInInterpolator;
 import android.support.v7.widget.RecyclerView;
@@ skipping 215 matching lines @@
         for (int i = 0; i < itemViewChildCount; ++i) {
             View snippetChild = ((ViewGroup) itemView).getChildAt(i);
             snippetChild.setAlpha(peekPadding / (float) mMaxPeekPadding);
         }
     }
 
     private static View inflateView(int resourceId, ViewGroup parent) {
         return LayoutInflater.from(parent.getContext()).inflate(resourceId, parent, false);
     }
 
-    public static boolean isCard(@NewTabPageItem.ViewType int type) {
+    public static boolean isCard(@ItemViewType int type) {
         switch (type) {
-            case NewTabPageItem.VIEW_TYPE_SNIPPET:
-            case NewTabPageItem.VIEW_TYPE_STATUS:
-            case NewTabPageItem.VIEW_TYPE_ACTION:
-            case NewTabPageItem.VIEW_TYPE_PROMO:
+            case ItemViewType.SNIPPET:
+            case ItemViewType.STATUS:
+            case ItemViewType.ACTION:
+            case ItemViewType.PROMO:
                 return true;
-            case NewTabPageItem.VIEW_TYPE_ABOVE_THE_FOLD:
-            case NewTabPageItem.VIEW_TYPE_HEADER:
-            case NewTabPageItem.VIEW_TYPE_SPACING:
-            case NewTabPageItem.VIEW_TYPE_PROGRESS:
-            case NewTabPageItem.VIEW_TYPE_FOOTER:
-            case NewTabPageItem.VIEW_TYPE_ALL_DISMISSED:
+            case ItemViewType.ABOVE_THE_FOLD:
+            case ItemViewType.HEADER:
+            case ItemViewType.SPACING:
+            case ItemViewType.PROGRESS:
+            case ItemViewType.FOOTER:
+            case ItemViewType.ALL_DISMISSED:
                 return false;
             default:
                 assert false;
         }
         return false;
     }
 
     @DrawableRes
     protected int selectBackground(boolean hasCardAbove, boolean hasCardBelow) {
         if (hasCardAbove && hasCardBelow) return R.drawable.ntp_card_middle;
         if (!hasCardAbove && hasCardBelow) return R.drawable.ntp_card_top;
         if (hasCardAbove && !hasCardBelow) return R.drawable.ntp_card_bottom;
         return R.drawable.ntp_card_single;
     }
 
     protected NewTabPageRecyclerView getRecyclerView() {
         return mRecyclerView;
     }
 }