MD Settings: Fix policy-related reentrancy crash for People page.

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 310 matching lines @@
   engine_start_timer_.reset(new base::OneShotTimer());
   engine_start_timer_->Start(FROM_HERE,
                              base::TimeDelta::FromSeconds(kTimeoutSec), this,
                              &PeopleHandler::DisplayTimeout);
 
   CallJavascriptFunction("cr.webUIListenerCallback",
                          base::StringValue("page-status-changed"),
                          base::StringValue(kSpinnerPageStatus));
 }
 
-// TODO(kochi): Handle error conditions other than timeout.
-// http://crbug.com/128692
 void PeopleHandler::DisplayTimeout() {
   // Stop a timer to handle timeout in waiting for checking network connection.
   engine_start_timer_.reset();
 
   // Do not listen to sync startup events.
   sync_startup_tracker_.reset();
 
   CallJavascriptFunction("cr.webUIListenerCallback",
                          base::StringValue("page-status-changed"),
                          base::StringValue(kTimeoutPageStatus));
@@ skipping 429 matching lines @@
   }
 #endif
 
   // Early exit if there is already a preferences push pending sync startup.
   if (sync_startup_tracker_)
     return;
 
   ProfileSyncService* service = GetSyncService();
   DCHECK(service);
   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
     // http://crbug.com/244769).
     if (SyncStartupTracker::GetSyncServiceState(profile_) !=
         SyncStartupTracker::SYNC_STARTUP_ERROR) {
       DisplaySpinner();
     }
-
-    // Start SyncSetupTracker to wait for sync to initialize.
-    sync_startup_tracker_.reset(new SyncStartupTracker(profile_, this));
     return;
   }
 
   configuring_sync_ = true;
   DCHECK(service->IsEngineInitialized())
       << "Cannot configure sync until the sync engine is initialized";
 
   // Setup args for the sync configure screen:
   //   syncAllDataTypes: true if the user wants to sync everything
   //   <data_type>Registered: true if the associated data type is supported
@@ skipping 107 matching lines @@
   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