[NTP Client] Check we are on the NTP after dismissal animation.

When dismissing a suggestion through the context menu, it is possible
that by the time the animation ends, we navigated away from the NTP
and it got destroyed, resulting in an NPE. We now exit early when
that is the case.

This CL also reverts the ineffective tentative fix from
https://codereview.chromium.org/2553163002

BUG=668945

Review-Url: https://codereview.chromium.org/2614753002
Cr-Commit-Position: refs/heads/master@{#441917}

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

@@ -7,7 +7,6 @@ package org.chromium.chrome.browser.ntp;
 import android.app.Activity;
 import android.support.annotation.IntDef;
 import android.support.annotation.StringRes;
-import android.support.v13.view.ViewCompat;
 import android.view.ContextMenu;
 import android.view.Menu;
 import android.view.MenuItem;
@@ -81,7 +80,7 @@ public class ContextMenuManager implements OnCloseContextMenuListener {
      *                 are tapped.
      */
     public void createContextMenu(ContextMenu menu, View associatedView, Delegate delegate) {
-        OnMenuItemClickListener listener = new ItemClickListener(delegate, associatedView);
+        OnMenuItemClickListener listener = new ItemClickListener(delegate);
         boolean hasItems = false;
 
         for (@ContextMenuItemId int itemId : MenuItemLabelMatcher.STRING_MAP.keySet()) {
@@ -168,23 +167,13 @@ public class ContextMenuManager implements OnCloseContextMenuListener {
 
     private static class ItemClickListener implements OnMenuItemClickListener {
         private final Delegate mDelegate;
-        private final View mAssociatedView;
 
-        ItemClickListener(Delegate delegate, View associatedView) {
+        ItemClickListener(Delegate delegate) {
             mDelegate = delegate;
-            mAssociatedView = associatedView;
         }
 
         @Override
         public boolean onMenuItemClick(MenuItem item) {
-            // If the user clicks a snippet then immediately long presses they will create a context
-            // menu while the snippet's URL loads in the background. This means that when they press
-            // an item on context menu the NTP will not actually be open. We add this check here to
-            // prevent taking any action if the user has left the NTP. (https://crbug.com/640468)
-            // Although the menu is supposed to be closed when we navigate away from the NTP, we
-            // have to keep this check because of race conditions. (https://crbug.com/668945)
-            if (!ViewCompat.isAttachedToWindow(mAssociatedView)) return true;
-
             switch (item.getItemId()) {
                 case ID_OPEN_IN_NEW_WINDOW:
                     mDelegate.openItem(WindowOpenDisposition.NEW_WINDOW);

chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/NewTabPageRecyclerView.java

@@ -12,6 +12,7 @@ import android.content.Context;
 import android.content.res.Resources;
 import android.graphics.Canvas;
 import android.graphics.Region;
+import android.support.v4.view.ViewCompat;
 import android.support.v4.view.animation.FastOutLinearInInterpolator;
 import android.support.v4.view.animation.LinearOutSlowInInterpolator;
 import android.support.v7.widget.LinearLayoutManager;
@@ -548,6 +549,10 @@ public class NewTabPageRecyclerView extends RecyclerView implements TouchDisable
 
             @Override
             public void onAnimationEnd(Animator animation) {
+                // It is possible that by the time the animation ends, we navigated away from the
+                // container and it got destroyed. In that case, abort. (https://crbug.com/668945)
+                if (!ViewCompat.isAttachedToWindow(viewHolder.itemView)) return;
+
                 dismissItemInternal(viewHolder);
                 NewTabPageRecyclerView.this.onItemDismissFinished(viewHolder);
             }