[NTP Snippets] Stop refreshing the snippets on tab switch

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

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPageView.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPageView.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPageView.java
index afc984a3bc586c1826cc3a7b5d549cb1d9637fa3..651d1867bff406c00981b648ed8814a213cfddf9 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPageView.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPageView.java
@@ -50,7 +50,6 @@
 import org.chromium.chrome.browser.ntp.snippets.SnippetsBridge.SnippetsObserver;
 import org.chromium.chrome.browser.profiles.MostVisitedSites.MostVisitedURLsObserver;
 import org.chromium.chrome.browser.profiles.MostVisitedSites.ThumbnailCallback;
-import org.chromium.chrome.browser.tab.TabObserver;
 import org.chromium.chrome.browser.util.ViewUtils;
 import org.chromium.chrome.browser.widget.RoundedIconGenerator;
 import org.chromium.ui.base.DeviceFormFactor;
@@ -164,9 +163,6 @@
         /** Sets the observer that will be notified of new snippets. */
         void setSnippetsObserver(SnippetsObserver observer);
 
-        /** Registers a {@link TabObserver} for the NTP. */
-        void addTabObserver(TabObserver tabObserver);
-
         /**
          * Gets a cached thumbnail of a URL.
          * @param url The URL whose thumbnail is being retrieved.