[NTP Snippets] Stop refreshing the snippets on tab switch

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 a68ed5d6f7c4953ab21a74f5ec8e27eb77e460f5..1652fbc480eafa39b95eef98ada6a60af7fcc993 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
@@ -535,12 +535,6 @@ public void onSnippetDismissed(SnippetArticle dismissedSnippet) {
             NewTabPageUma.recordSnippetAction(NewTabPageUma.SNIPPETS_ACTION_DISMISSED);
             mSnippetsBridge.discardSnippet(dismissedSnippet);
         }
-
-        @Override
-        public void addTabObserver(TabObserver tabObserver) {
-            if (mIsDestroyed) return;
-            mTab.addObserver(tabObserver);
-        }
     };
 
     /**