[NTP::SectionOrder] Propagate category rank from UI through the bridge.

chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPage.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPage.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPage.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPage.java
index 1d5a8082c671fa145c82b3b447ced5cd12812b71..b683aa3f09562f9d9308c17ff0e4432f340169e1 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPage.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPage.java
@@ -368,9 +368,15 @@ public class NewTabPage
             }
         }
 
+        public void trackSnippetOpened(
+                int windowOpenDisposition, SnippetArticle article, int categoryIndex) {
+            mSnippetsBridge.onSuggestionOpened(article, categoryIndex, windowOpenDisposition);
+        }
+
         @Override
-        public void openSnippet(int windowOpenDisposition, SnippetArticle article) {
-            mSnippetsBridge.onSuggestionOpened(article, windowOpenDisposition);
+        public void openSnippet(
+                int windowOpenDisposition, SnippetArticle article, int categoryIndex) {
+            trackSnippetOpened(windowOpenDisposition, article, categoryIndex);
             NewTabPageUma.recordAction(NewTabPageUma.ACTION_OPENED_SNIPPET);
 
             if (article.mIsAssetDownload) {