Fix a crash on clearing power consumption auditing data in guest mode.

chrome/browser/browsing_data/browsing_data_remover.cc

 // Copyright (c) 2012 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/browsing_data/browsing_data_remover.h"
 
 #include <map>
 #include <set>
 #include <string>
 
@@ skipping 292 matching lines @@
       // were active on. It therefore indirectly stores details of websites a
       // user has visited so best clean from here as well.
       extensions::ActivityLog::GetInstance(profile_)->RemoveURLs(restrict_urls);
 #endif
     }
 
     // The power consumption history by origin contains details of websites
     // that were visited.
     power::OriginPowerMap* origin_power_map =
         power::OriginPowerMapFactory::GetForBrowserContext(profile_);
-    origin_power_map->ClearOriginMap();
+    if (origin_power_map)
+      origin_power_map->ClearOriginMap();
 
     // Need to clear the host cache and accumulated speculative data, as it also
     // reveals some history: we have no mechanism to track when these items were
     // created, so we'll clear them all. Better safe than sorry.
     if (g_browser_process->io_thread()) {
       waiting_for_clear_hostname_resolution_cache_ = true;
       BrowserThread::PostTask(
           BrowserThread::IO, FROM_HERE,
           base::Bind(
               &BrowsingDataRemover::ClearHostnameResolutionCacheOnIOThread,
@@ skipping 879 matching lines @@
   waiting_for_clear_webrtc_logs_ = false;
   NotifyAndDeleteIfDone();
 }
 #endif
 
 void BrowsingDataRemover::OnClearedDomainReliabilityMonitor() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   waiting_for_clear_domain_reliability_monitor_ = false;
   NotifyAndDeleteIfDone();
 }