📰 Record the first scroll event on the recycler view

chrome/android/java/src/org/chromium/chrome/browser/suggestions/SuggestionsMetrics.java

Index: chrome/android/java/src/org/chromium/chrome/browser/suggestions/SuggestionsMetrics.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/suggestions/SuggestionsMetrics.java b/chrome/android/java/src/org/chromium/chrome/browser/suggestions/SuggestionsMetrics.java
index fa64959c56832b0d46598f9a1f39b8dec2155b08..e69d3391bcdd74052a17ad0e296964b50f813d4c 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/suggestions/SuggestionsMetrics.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/suggestions/SuggestionsMetrics.java
@@ -4,6 +4,8 @@
 
 package org.chromium.chrome.browser.suggestions;
 
+import android.support.v7.widget.RecyclerView;
+
 import org.chromium.base.metrics.RecordUserAction;
 
 /**
@@ -43,4 +45,24 @@ public static void recordCardSwipedAway() {
     public static void recordActionViewAll() {
         RecordUserAction.record("Suggestions.Category.ViewAll");
     }
+
+    /**
+     * One-shot reporter that records the first time the user scrolls a {@link RecyclerView}. If it
+     * should be reused, call {@link #reset()} to rearm it.
+     */
+    public static class ScrollEventReporter extends RecyclerView.OnScrollListener {
+        private boolean mFired;
+        @Override
+        public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
+            if (mFired) return;
+            if (newState != RecyclerView.SCROLL_STATE_DRAGGING) return;
+
+            RecordUserAction.record("Suggestions.ScrolledAfterOpen");
+            mFired = true;
+        }
+
+        public void reset() {
+            mFired = false;
+        }
+    }
 }