Initial clear server data impl

components/browser_sync/profile_sync_service.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 "components/browser_sync/profile_sync_service.h"
 
 #include <stddef.h>
 
 #include <cstddef>
 #include <map>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/command_line.h"
 #include "base/feature_list.h"
 #include "base/files/file_util.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/metrics/histogram.h"
 #include "base/profiler/scoped_tracker.h"
+#include "base/run_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/stringprintf.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "components/autofill/core/common/autofill_pref_names.h"
 #include "components/browser_sync/browser_sync_switches.h"
 #include "components/history/core/browser/typed_url_data_type_controller.h"
 #include "components/invalidation/impl/invalidation_prefs.h"
 #include "components/invalidation/public/invalidation_service.h"
 #include "components/pref_registry/pref_registry_syncable.h"
@@ skipping 1345 matching lines @@
 }
 
 bool ProfileSyncService::IsFirstSetupInProgress() const {
   DCHECK(thread_checker_.CalledOnValidThread());
   return !IsFirstSetupComplete() && startup_controller_->IsSetupInProgress();
 }
 
 std::unique_ptr<syncer::SyncSetupInProgressHandle>
 ProfileSyncService::GetSetupInProgressHandle() {
   DCHECK(thread_checker_.CalledOnValidThread());
+
   if (++outstanding_setup_in_progress_handles_ == 1) {
     DCHECK(!startup_controller_->IsSetupInProgress());
     startup_controller_->SetSetupInProgress(true);
 
     NotifyObservers();
   }
 
   return std::unique_ptr<syncer::SyncSetupInProgressHandle>(
       new syncer::SyncSetupInProgressHandle(
           base::Bind(&ProfileSyncService::OnSetupInProgressHandleDestroyed,
@@ skipping 1020 matching lines @@
     return;
 
   DCHECK(startup_controller_->IsSetupInProgress());
   startup_controller_->SetSetupInProgress(false);
 
   if (IsEngineInitialized())
     ReconfigureDatatypeManager();
   NotifyObservers();
 }
 
+void ProfileSyncService::ClearServerDataForTest(const base::Closure& callback) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  engine_->StartConfiguration();

[skym, 2017/03/07 21:32:25]

I was always confused about this, why do you call StartConfiguration there
again? Can you add a comment explaining the reasoning here?

[wylieb, 2017/03/07 23:04:40]

This is the only place I call StartConfiguration. I do it because the engine
needs to be in configuration mode in order to call ClearServerData!

[skym, 2017/03/08 00:23:48]

Heh, sorry, I said "again" because I've asked you this question before, but
don't remember the reason.

Digging into the code, it looks like the SyncScheduler has a concept of modes,
and requires, as you were indicating, a CONFIGURATION_MODE to be set to
transition to CLEAR_SERVER_DATA_MODE.

https://cs.chromium.org/chromium/src/components/sync/engine_impl/sync_schedul...
https://cs.chromium.org/chromium/src/components/sync/engine_impl/sync_schedul...
https://codereview.chromium.org/1251203002/

I still don't quite follow the reason for this restriction. Perhaps it's because
the only place we currently call this is after a catch up configuration sync
cycle
https://cs.chromium.org/chromium/src/components/browser_sync/profile_sync_ser...
. Pavel, do you have better understanding for this restriction?

Regardless, Brandon, can you slap in a comment here explaining this? Your logic
doesn't care about "configuration", whatever that means in this context. But the
engine/scheduler seem to have this restriction and calling
engine_->StartConfiguration() essentially hacks around this confusing
restriction.

+  engine_->ClearServerData(callback);
+}
+
 }  // namespace browser_sync