MD Settings: Fix policy-related ProfileSyncService crashes.

chrome/browser/ui/webui/settings/people_handler.cc

 // 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.
 
 #include "chrome/browser/ui/webui/settings/people_handler.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 757 matching lines @@
       SigninErrorControllerFactory::GetForProfile(profile_)->HasError()) {
     return;
   }
 #endif
 
   // Early exit if there is already a preferences push pending sync startup.
   if (sync_startup_tracker_)
     return;
 
   ProfileSyncService* service = GetSyncService();
-  DCHECK(service);
+  // The sync service may be nullptr if it has been just disabled by policy.
+  if (!service)
+    return;
+
   if (!service->IsEngineInitialized()) {
     // Requesting the sync service to start may trigger another reentrant call
     // to PushSyncPrefs. Setting up the startup tracker beforehand correctly
     // signals the re-entrant call to early exit.
     sync_startup_tracker_.reset(new SyncStartupTracker(profile_, this));
     service->RequestStart();
 
     // See if it's even possible to bring up the sync engine - if not
     // (unrecoverable error?), don't bother displaying a spinner that will be
     // immediately closed because this leads to some ugly infinite UI loop (see
@@ skipping 107 matching lines @@
                          base::StringValue("sync-status-changed"),
                          *GetSyncStatusDictionary());
 }
 
 void PeopleHandler::MarkFirstSetupComplete() {
   // Suppress the sign in promo once the user starts sync. This way the user
   // doesn't see the sign in promo even if they sign out later on.
   signin::SetUserSkippedPromo(profile_);
 
   ProfileSyncService* service = GetSyncService();
-  DCHECK(service);
-  if (service->IsFirstSetupComplete())
+  // The sync service may be nullptr if it has been just disabled by policy.
+  if (!service || service->IsFirstSetupComplete())

[Dan Beam, 2016/12/22 22:07:40]

nit: is there somehow we can check that if !service that we're disabled by
policy?

[tommycli, 2016/12/22 22:46:16]

Well... it's more like, GetSyncService() returns nullptr if
profile->IsSyncAllowed() is false:
https://codesearch.chromium.org/chromium/src/chrome/browser/ui/webui/settings...

So adding a DCHECK would be pretty tautological.

     return;
 
   // This is the first time configuring sync, so log it.
   base::FilePath profile_file_path = profile_->GetPath();
   ProfileMetrics::LogProfileSyncSignIn(profile_file_path);
 
   // We're done configuring, so notify ProfileSyncService that it is OK to
   // start syncing.
   sync_blocker_.reset();
   service->SetFirstSetupComplete();
 }
 
 }  // namespace settings