[Android] Do not restore NTPs from disk unless they are selected.

chrome/android/javatests/src/org/chromium/chrome/browser/TabsTest.java

 // Copyright 2015 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;
 
 import static org.chromium.base.test.util.Restriction.RESTRICTION_TYPE_NON_LOW_END_DEVICE;
 
 import android.content.DialogInterface;
 import android.content.pm.ActivityInfo;
@@ skipping 1787 matching lines @@
             }
         });
 
         assertTrue("WebContentsObserver was never destroyed", webContentsDestroyCalled.get());
     }
 
     @MediumTest
     @Feature({"Android-TabSwitcher"})
     @RetryOnFailure
     public void testIncognitoTabsNotRestoredAfterSwipe() throws Exception {
+        mTestServer = EmbeddedTestServer.createAndStartServer(getInstrumentation().getContext());
+        startMainActivityWithURL(mTestServer.getURL(TEST_PAGE_FILE_PATH));
+
         newIncognitoTabFromMenu();
+        // Tab states are not saved for empty NTP tabs, so navigate to any page to trigger a file
+        // to be saved.
+        loadUrl(mTestServer.getURL(TEST_PAGE_FILE_PATH));
 
         File tabStateDir = TabbedModeTabPersistencePolicy.getOrCreateTabbedModeStateDirectory();
         TabModel normalModel = getActivity().getTabModelSelector().getModel(false);
         TabModel incognitoModel = getActivity().getTabModelSelector().getModel(true);
         File normalTabFile = new File(tabStateDir,
                 TabState.getTabStateFilename(
                         normalModel.getTabAt(normalModel.getCount() - 1).getId(), false));
         File incognitoTabFile = new File(tabStateDir,
                 TabState.getTabStateFilename(incognitoModel.getTabAt(0).getId(), true));
 
@@ skipping 13 matching lines @@
     @Override
     public void startMainActivity() throws InterruptedException {
         float dpToPx = getInstrumentation().getContext().getResources().getDisplayMetrics().density;
         mPxToDp = 1.0f / dpToPx;
 
         // Exclude the tests that can launch directly to a page other than the NTP.
         if (getName().equals("testOpenAndCloseNewTabButton")
                 || getName().equals("testSwitchToTabThatDoesNotHaveThumbnail")
                 || getName().equals("testCloseTabPortrait")
                 || getName().equals("testCloseTabLandscape")
-                || getName().equals("testTabsAreDestroyedOnModelDestruction")) {
+                || getName().equals("testTabsAreDestroyedOnModelDestruction")
+                || getName().equals("testIncognitoTabsNotRestoredAfterSwipe")) {
             return;
         }
         startMainActivityFromLauncher();
     }
 
     private void assertFileExists(final File fileToCheck, final boolean expected)
             throws InterruptedException {
         CriteriaHelper.pollInstrumentationThread(
                     Criteria.equals(expected, new Callable<Boolean>() {
                         @Override
                         public Boolean call() {
                             return fileToCheck.exists();
                         }
                     }));
     }
 }