Ntp: restore scroll position.

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 54a70948c5dc48ef31bc798cb48c1506cb9023cd..e6c186568bd81c8166621e6181ed908445657083 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
@@ -257,6 +257,20 @@ public class NewTabPageRecyclerView extends RecyclerView {
     }
 
     /**
+     * Returns the approximate adapter position that the user has scrolled to. The purpose of this
+     * value is that it can be stored and later retrieved to restore a scroll position that is
+     * familiar to the user, showing (part of) the same content the user was previously looking at.
+     * This position is valid for that purpose regardless of device orientation changes. Note that
+     * if the underlying data has changed in the meantime, different content would be shown for this
+     * position.
+     */
+    public int getScrollPosition() {
+        int position = mLayoutManager.findFirstVisibleItemPosition();
+        if (position == NO_POSITION) position = 0;

[Bernhard Bauer, 2016/09/16 15:02:50]

Actually, we could probably return NO_POSITION in this case as well, and then
just not write it to the NavigationEntry.

[Michael van Ouwerkerk, 2016/09/16 16:35:05]

Done.

+        return position;
+    }
+
+    /**
      * Finds the view holder for the first header.
      * @return The {@code ViewHolder} of the header, or null if it is not present.
      */