Fix crash on chrome://sync-internals when sync is disabled.

chrome/browser/ui/webui/sync_internals_message_handler.cc

 // Copyright 2014 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/webui/sync_internals_message_handler.h"
 
 #include <vector>
 
 #include "base/logging.h"
 #include "chrome/browser/profiles/profile.h"
@@ skipping 77 matching lines @@
     js_controller_ = service->GetJsController();
     js_controller_->AddJsEventHandler(this);
     is_registered_ = true;
   }
 }
 
 void SyncInternalsMessageHandler::HandleRegisterForPerTypeCounters(
     const base::ListValue* args) {
   DCHECK(args->empty());
 
-  ProfileSyncService* service = GetProfileSyncService();
-  if (service && !is_registered_for_counters_) {
-    service->AddTypeDebugInfoObserver(this);
-    is_registered_for_counters_ = true;
-  } else {
-    // Re-register to ensure counters get re-emitted.
-    service->RemoveTypeDebugInfoObserver(this);
-    service->AddTypeDebugInfoObserver(this);
+  if (ProfileSyncService* service = GetProfileSyncService()) {
+    if (!is_registered_for_counters_) {
+      service->AddTypeDebugInfoObserver(this);
+      is_registered_for_counters_ = true;
+    } else {
+      // Re-register to ensure counters get re-emitted.
+      service->RemoveTypeDebugInfoObserver(this);
+      service->AddTypeDebugInfoObserver(this);
+    }
   }
 }
 
 void SyncInternalsMessageHandler::HandleRequestUpdatedAboutInfo(
     const base::ListValue* args) {
   DCHECK(args->empty());
   SendAboutInfo();
 }
 
 void SyncInternalsMessageHandler::HandleRequestListOfTypes(
@@ skipping 100 matching lines @@
       *value);
 }
 
 // Gets the ProfileSyncService of the underlying original profile.
 // May return NULL (e.g., if sync is disabled on the command line).
 ProfileSyncService* SyncInternalsMessageHandler::GetProfileSyncService() {
   Profile* profile = Profile::FromWebUI(web_ui());
   ProfileSyncServiceFactory* factory = ProfileSyncServiceFactory::GetInstance();
   return factory->GetForProfile(profile->GetOriginalProfile());
 }