Check for null on Browser pointer to address crash report.

chrome/browser/ui/search/instant_page.cc

 // Copyright 2013 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.
 
 #include "chrome/browser/ui/search/instant_page.h"
 
 #include "apps/app_launcher.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/history/most_visited_tiles_experiment.h"
@@ skipping 282 matching lines @@
 }
 
 void InstantPage::MaybeRemoveMostVisitedItems(
     std::vector<InstantMostVisitedItem>* items) {
 // The code below uses APIs not available on Android and the experiment should
 // not run there.
 #if !defined(OS_ANDROID)
   if (!history::MostVisitedTilesExperiment::IsDontShowOpenURLsEnabled())
     return;
 
-  TabStripModel* tab_strip_model = chrome::FindBrowserWithProfile(
-      profile_,
-      chrome::GetActiveDesktop())->tab_strip_model();
+  Browser* browser = chrome::FindBrowserWithProfile(profile_,
+                                                    chrome::GetActiveDesktop());
+  if (!browser)
+    return;
+
+  TabStripModel* tab_strip_model = browser->tab_strip_model();
   history::TopSites* top_sites = profile_->GetTopSites();
   if (!tab_strip_model || !top_sites) {
     NOTREACHED();
     return;
   }
 
   std::set<std::string> open_urls;
   chrome::GetOpenUrls(*tab_strip_model, *top_sites, &open_urls);
   history::MostVisitedTilesExperiment::RemoveItemsMatchingOpenTabs(
       open_urls, items);
 
 #endif
 }