Refine snap scrolling on the Cards New Tab Page.

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

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/NewTabPageRecyclerView.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/NewTabPageRecyclerView.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/NewTabPageRecyclerView.java
index e6f2003ecf5fc2304d299fb03663901130c0dc6e..f7ff60b8772160843bd67b7216fa4c17e19452c4 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/NewTabPageRecyclerView.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/NewTabPageRecyclerView.java
@@ -192,6 +192,18 @@ public class NewTabPageRecyclerView extends RecyclerView {
         }
     }
 
+    public boolean isPeekingCardVisible() {
+        return findFirstCard() != null;
+    }
+
+    public int getPeekingCardTop() {
+        return findFirstCard().itemView.getTop();
+    }
+
+    public int getPeekingCardHeight() {
+        return findFirstCard().itemView.getHeight();
+    }
+
     /**
      * Finds the first card in this RecyclerView.
      * @return The viewholder for the first card or null if no card is available.
@@ -244,4 +256,31 @@ public class NewTabPageRecyclerView extends RecyclerView {
         mCompensationHeight -= itemView.getHeight();
         assert mCompensationHeight >= 0;
     }
+
+    /**
+     * If the RecyclerView is currently scrolled to between regionStart and regionEnd, smooth scroll
+     * out of the region. flipPoint is the threshold used to decide which bound of the region to
+     * scroll to. It returns whether the view was scrolled.
+     */
+    public boolean scrollOutOfRegion(int regionStart, int flipPoint, int regionEnd) {
+        // This function is only called when we are using the RecyclerView.
+        final int currentScroll = computeVerticalScrollOffset();
+
+        if (currentScroll < regionStart || currentScroll > regionEnd) return false;
+
+        if (currentScroll < flipPoint) {
+            smoothScrollBy(0, regionStart - currentScroll);
+        } else {
+            smoothScrollBy(0, regionEnd - currentScroll);
+        }
+        return true;
+    }
+
+    /**
+     * If the RecyclerView is currently scrolled to between regionStart and regionEnd, smooth scroll
+     * out of the region to the nearest edge.
+     */
+    public boolean scrollOutOfRegion(int regionStart, int regionEnd) {
+        return scrollOutOfRegion(regionStart, (regionStart + regionEnd) / 2, regionEnd);
+    }
 }