[NTP Snippets] Fill space below the last snippet if necessary

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

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SpacingListItem.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SpacingListItem.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SpacingListItem.java
new file mode 100644
index 0000000000000000000000000000000000000000..2153d0905d48437a4dc7dd5231891c83d0fcad7a
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SpacingListItem.java
@@ -0,0 +1,38 @@
+// 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.content.Context;
+import android.view.View;
+import android.view.ViewGroup;
+
+/**
+ * Placeholder item to let the snippets flow to the top of the scroll list even when it does not
+ * contain enough of them. It is displayed as a dummy item with variable height that just occupies
+ * the remaining space between the last item in the RecyclerView and the bottom of the screen.
+ */
+public class SpacingListItem implements NewTabPageListItem {
+    private static class SpacingListItemView extends View {
+        public SpacingListItemView(Context context) {
+            super(context);
+        }
+
+        @Override
+        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+            setMeasuredDimension(
+                    0, ((NewTabPageRecyclerView) getParent()).calculateBottomSpacing());
+        }
+    }
+
+    /** Creates the View object for displaying the variable spacing. */
+    public static View createView(ViewGroup parent) {
+        return new SpacingListItemView(parent.getContext());
+    }
+
+    @Override
+    public int getType() {
+        return NewTabPageListItem.VIEW_TYPE_SPACING;
+    }
+}