Add a null check to ChromeActivity#onStartWithNative()

chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.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 android.annotation.SuppressLint;
 import android.annotation.TargetApi;
 import android.app.Activity;
 import android.app.SearchManager;
@@ skipping 560 matching lines @@
             createContextReporterIfNeeded();
         } else {
             ContextReporter.reportStatus(ContextReporter.STATUS_GSA_NOT_AVAILABLE);
         }
         mCompositorViewHolder.resetFlags();
 
         // postDeferredStartupIfNeeded() is called in TabModelSelectorTabObsever#onLoadStopped(),
         // #onPageLoadFinished() and #onCrash(). If we are not actively loading a tab (e.g.
         // in Android N multi-instance, which is created by re-parenting an existing tab),
         // ensure onDeferredStartup() gets called by calling postDeferredStartupIfNeeded() here.
-        if (!getActivityTab().isLoading()) {
+        if (getActivityTab() == null || !getActivityTab().isLoading()) {
             postDeferredStartupIfNeeded();
         }
     }
 
     @Override
     public void onWindowFocusChanged(boolean hasFocus) {
         super.onWindowFocusChanged(hasFocus);
         Tab tab = getActivityTab();
         if (tab == null) return;
         if (hasFocus) {
@@ skipping 1149 matching lines @@
                 "Android.MultiWindowMode.IsTabletScreenWidthBelow600",
                 mScreenWidthDp < DeviceFormFactor.MINIMUM_TABLET_WIDTH_DP);
 
         if (mScreenWidthDp < DeviceFormFactor.MINIMUM_TABLET_WIDTH_DP) {
             RecordHistogram.recordLinearCountHistogram(
                     "Android.MultiWindowMode.TabletScreenWidth", mScreenWidthDp, 1,
                     DeviceFormFactor.MINIMUM_TABLET_WIDTH_DP, 50);
         }
     }
 }