[Suggestions] Remove TreeNode.getSuggestionAt() in favor of a visitor.

chrome/android/javatests/src/org/chromium/chrome/browser/ntp/cards/NewTabPageRecyclerViewTest.java

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.ntp.cards;
 
 import android.content.res.Resources;
 import android.support.test.InstrumentationRegistry;
 import android.support.test.filters.MediumTest;
 import android.support.v7.widget.RecyclerView;
@@ skipping 118 matching lines @@
 
     @Test
     @MediumTest
     @Feature({"NewTabPage"})
     public void testClickSuggestion() throws InterruptedException {
         setSuggestionsAndWaitForUpdate(10);
         List<SnippetArticle> suggestions = mSource.getSuggestionsForCategory(TEST_CATEGORY);
 
         // Scroll the last suggestion into view and click it.
         SnippetArticle suggestion = suggestions.get(suggestions.size() - 1);
-        int suggestionPosition = getSuggestionPosition(suggestion);
+        int suggestionPosition = getLastCardPosition();
         final View suggestionView = getViewHolderAtPosition(suggestionPosition).itemView;
         ChromeTabUtils.waitForTabPageLoaded(mTab, new Runnable() {
             @Override
             public void run() {
                 TouchCommon.singleClickView(suggestionView);
             }
         });
         Assert.assertEquals(suggestion.mUrl, mTab.getUrl());
     }
 
@@ skipping 32 matching lines @@
 
     @Test
     @MediumTest
     @Feature({"NewTabPage"})
     public void testDismissArticleWithContextMenu() throws InterruptedException, TimeoutException {
         setSuggestionsAndWaitForUpdate(10);
         List<SnippetArticle> suggestions = mSource.getSuggestionsForCategory(TEST_CATEGORY);
         Assert.assertEquals(10, suggestions.size());
 
         // Scroll a suggestion into view.
-        int suggestionPosition = getSuggestionPosition(suggestions.get(suggestions.size() - 1));
+        int suggestionPosition = getLastCardPosition();
         View suggestionView = getViewHolderAtPosition(suggestionPosition).itemView;
 
         // Dismiss the suggestion using the context menu.
         invokeContextMenu(suggestionView, ContextMenuManager.ID_REMOVE);
         RecyclerViewTestUtils.waitForViewToDetach(getRecyclerView(), suggestionView);
 
         suggestions = mSource.getSuggestionsForCategory(TEST_CATEGORY);
         Assert.assertEquals(9, suggestions.size());
     }
 
@@ skipping 152 matching lines @@
     }
 
     private NewTabPageRecyclerView getRecyclerView() {
         return getNtpView().getRecyclerView();
     }
 
     private NewTabPageAdapter getAdapter() {
         return getRecyclerView().getNewTabPageAdapter();
     }
 
-    private int getSuggestionPosition(SnippetArticle article) {
-        NewTabPageAdapter adapter = getAdapter();
-        for (int i = 0; i < adapter.getItemCount(); i++) {
-            SnippetArticle articleToCheck = adapter.getSuggestionAt(i);
-            if (articleToCheck != null && articleToCheck.equals(article)) return i;
+    private int getLastCardPosition() {
+        int count = getAdapter().getItemCount();
+        for (int i = count - 1; i >= 0; i--) {
+            if (getAdapter().getItemViewType(i) == ItemViewType.SNIPPET) return i;
         }
         return RecyclerView.NO_POSITION;
     }
 
     /**
      * Scroll the {@link View} at the given adapter position into view and returns
      * its {@link ViewHolder}.
      * @param position the adapter position for which to return the {@link ViewHolder}.
      * @return the ViewHolder for the given {@code position}.
      */
@@ skipping 57 matching lines @@
         TestTouchUtils.longClickView(InstrumentationRegistry.getInstrumentation(), view);
         Assert.assertTrue(InstrumentationRegistry.getInstrumentation().invokeContextMenuAction(
                 mActivityTestRule.getActivity(), contextMenuItemId, 0));
     }
 
 
     private static void assertArrayEquals(int[] expected, int[] actual) {
         Assert.assertEquals(Arrays.toString(expected), Arrays.toString(actual));
     }
 }