Revert of Ntp: restore scroll position.

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 7d96a05a5dc7fe5c32cef8929ab3364c90d22393..f5b0d2773ef74a89c6ead1aa7607ea08107cd4f1 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
@@ -13,7 +13,6 @@
 import android.os.Build;
 import android.os.SystemClock;
 import android.support.v4.view.ViewCompat;
-import android.support.v7.widget.RecyclerView;
 import android.view.ContextMenu;
 import android.view.LayoutInflater;
 import android.view.Menu;
@@ -23,7 +22,6 @@
 import org.chromium.base.ApiCompatibilityUtils;
 import org.chromium.base.Callback;
 import org.chromium.base.CommandLine;
-import org.chromium.base.Log;
 import org.chromium.base.ThreadUtils;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.base.metrics.RecordHistogram;
@@ -71,8 +69,6 @@
 import org.chromium.chrome.browser.tabmodel.document.TabDelegate;
 import org.chromium.chrome.browser.util.UrlUtilities;
 import org.chromium.content_public.browser.LoadUrlParams;
-import org.chromium.content_public.browser.NavigationController;
-import org.chromium.content_public.browser.NavigationEntry;
 import org.chromium.content_public.common.Referrer;
 import org.chromium.net.NetworkChangeNotifier;
 import org.chromium.ui.WindowOpenDisposition;
@@ -90,7 +86,6 @@
  */
 public class NewTabPage
         implements NativePage, InvalidationAwareThumbnailProvider, TemplateUrlServiceObserver {
-    private static final String TAG = "NewTabPage";
 
     // MostVisitedItem Context menu item IDs.
     static final int ID_OPEN_IN_NEW_WINDOW = 0;
@@ -107,9 +102,6 @@
     private static final int STATIC_LOGO_CLICKED = 0;
     private static final int CTA_IMAGE_CLICKED = 1;
     private static final int ANIMATED_LOGO_CLICKED = 2;
-
-    // Key for the scroll position data that may be stored in a navigation entry.
-    private static final String NAVIGATION_ENTRY_SCROLL_POSITION_KEY = "NewTabPageScrollPosition";
 
     private static final String CHROME_CONTENT_SUGGESTIONS_REFERRER =
             "https://www.googleapis.com/auth/chrome-content-suggestions";
@@ -673,20 +665,6 @@
             public void onHidden(Tab tab) {
                 if (mIsLoaded) recordNTPInteractionTime();
             }
-
-            @Override
-            public void onPageLoadStarted(Tab tab, String url) {
-                if (mTab.getWebContents() == null) return;
-
-                NavigationController controller = mTab.getWebContents().getNavigationController();
-                int index = controller.getLastCommittedEntryIndex();
-                NavigationEntry entry = controller.getEntryAtIndex(index);
-                if (entry == null) return;
-
-                assert isNTPUrl(entry.getUrl());
-                controller.setEntryExtraData(index, NAVIGATION_ENTRY_SCROLL_POSITION_KEY,
-                        Integer.toString(mNewTabPageView.getScrollPosition()));
-            }
         };
         mTab.addObserver(mTabObserver);
         mMostVisitedSites = buildMostVisitedSites(mProfile);
@@ -699,8 +677,7 @@
 
         LayoutInflater inflater = LayoutInflater.from(activity);
         mNewTabPageView = (NewTabPageView) inflater.inflate(R.layout.new_tab_page_view, null);
-        mNewTabPageView.initialize(mNewTabPageManager, mSearchProviderHasLogo, mSnippetsBridge,
-                getScrollPositionFromNavigationEntry());
+        mNewTabPageView.initialize(mNewTabPageManager, mSearchProviderHasLogo, mSnippetsBridge);
 
         RecordHistogram.recordBooleanHistogram(
                 "NewTabPage.MobileIsUserOnline", NetworkChangeNotifier.isOnline());
@@ -860,29 +837,6 @@
     }
 
     /**
-     * Returns the value of the adapter scroll position that was stored in the last committed
-     * navigation entry. Returns {@code RecyclerView.NO_POSITION} if there is no last committed
-     * navigation entry, or if no data is found.
-     * @return The adapter scroll position.
-     */
-    private int getScrollPositionFromNavigationEntry() {
-        if (mTab.getWebContents() == null) return RecyclerView.NO_POSITION;
-
-        NavigationController controller = mTab.getWebContents().getNavigationController();
-        int index = controller.getLastCommittedEntryIndex();
-        String scrollPositionData =
-                controller.getEntryExtraData(index, NAVIGATION_ENTRY_SCROLL_POSITION_KEY);
-        if (scrollPositionData == null) return RecyclerView.NO_POSITION;
-
-        try {
-            return Integer.parseInt(scrollPositionData);
-        } catch (NumberFormatException e) {
-            Log.w(TAG, "Bad data found for scroll position: %s", scrollPositionData, e);
-            return RecyclerView.NO_POSITION;
-        }
-    }
-
-    /**
      * @return Whether the NTP has finished loaded.
      */
     @VisibleForTesting