Add a snippet item decoration to recycler view for cards and make the card full bleed with a divide…

chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetItemDecoration.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetItemDecoration.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetItemDecoration.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetItemDecoration.java
new file mode 100644
index 0000000000000000000000000000000000000000..552b4c9dfa7c600c2943091b802c769252ece7ad
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetItemDecoration.java
@@ -0,0 +1,32 @@
+// 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.snippets;
+
+import android.content.Context;
+import android.graphics.Rect;
+import android.support.v7.widget.RecyclerView;
+import android.view.View;
+
+import org.chromium.chrome.R;
+
+/**
+ * A class that decorates the RecyclerView elements.
+ */
+public class SnippetItemDecoration extends RecyclerView.ItemDecoration {
+    private final int mVerticalSpace;
+
+    public SnippetItemDecoration(Context context) {
+        this.mVerticalSpace =
+                context.getResources().getDimensionPixelSize(R.dimen.snippets_vertical_space);
+    }
+
+    @Override
+    public void getItemOffsets(Rect outRect, View view, RecyclerView parent,

[newt (away), 2016/04/04 20:57:34]

The javadoc for getItemOffsets() says "If this ItemDecoration does not affect
the positioning of item views, it should set all four fields of
<code>outRect</code> (left, top, right, bottom) to zero before returning."
That's why I think you should call outRect.clear() as the first step in this
method.

[mcwilliams, 2016/04/05 09:58:37]

Done.

[newt (away), 2016/04/05 16:43:36]

Actually, you need to call outRect.setEmpty() outside the "if" statement.
According to the getItemOffsets() API, you always need to set all four fields on
outRect, not just modify some fields in some cases. (I imagine the resulting bug
would manifest itself as the bottom element having the wrong offsets in some
cases.)

If it's not clear *why* you need to call outRect.clear() in all cases, it's
probably because outRect is reused many times, and Android doesn't reset the
Rect object before passing it to another method. This is an optimization to
reduce garbage collection, but requires some extra care on the programmer's
part.

Could you fix this in a tiny follow-up CL?

[mcwilliams, 2016/04/05 17:29:08]

That makes sense :)
https://codereview.chromium.org/1857313002/

+            RecyclerView.State state) {
+        if (parent.getChildAdapterPosition(view) != parent.getAdapter().getItemCount() - 1) {
+            outRect.bottom = mVerticalSpace;
+        }
+    }
+}