Fix crashes in ExtensionService

chrome/browser/dom_ui/app_launcher_handler.cc

 // Copyright (c) 2011 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/dom_ui/app_launcher_handler.h"
 
 #include <string>
 #include <vector>
 
 #include "base/metrics/histogram.h"
@@ skipping 452 matching lines @@
 }
 
 // static
 void AppLauncherHandler::RecordAppLaunchByURL(
     Profile* profile,
     std::string escaped_url,
     extension_misc::AppLaunchBucket bucket) {
   CHECK(bucket != extension_misc::APP_LAUNCH_BUCKET_INVALID);
 
   GURL url(UnescapeURLComponent(escaped_url, kUnescapeRules));
-  if (!profile->GetExtensionService()->IsInstalledApp(url))
+  // TODO: the ExtensionService should never be NULL, but in some cases it is,
+  // see bug 73768. After it is resolved, the explicit test can go away.
+  ExtensionService* service = profile->GetExtensionService();
+  if (!service || !service->IsInstalledApp(url))
     return;
 
   UMA_HISTOGRAM_ENUMERATION(extension_misc::kAppLaunchHistogram, bucket,
                             extension_misc::APP_LAUNCH_BUCKET_BOUNDARY);
 }
 
 void AppLauncherHandler::InstallUIProceed() {
   DCHECK(!extension_id_prompting_.empty());
 
   // The extension can be uninstalled in another window while the UI was
@@ skipping 20 matching lines @@
 
 void AppLauncherHandler::UninstallDefaultApps() {
   DefaultApps* default_apps = extensions_service_->default_apps();
   const ExtensionIdSet& app_ids = default_apps->default_apps();
   for (ExtensionIdSet::const_iterator iter = app_ids.begin();
        iter != app_ids.end(); ++iter) {
     if (extensions_service_->GetExtensionById(*iter, true))
       extensions_service_->UninstallExtension(*iter, false);
   }
 }