Ntp: add ripple to suggestion cards.

BUG=614320

Review-Url: https://codereview.chromium.org/2360723002
Cr-Commit-Position: refs/heads/master@{#420589}

chrome/android/java/res/layout/new_tab_page_snippets_card.xml

@@ -9,6 +9,7 @@
     android:id="@+id/snippets_card_view"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
+    android:foreground="@drawable/button_borderless_compat"
     android:padding="@dimen/snippets_padding_and_peeking_card_height"
     android:background="@drawable/ntp_card_single">