[Sync] Always upload stack traces for USS DeviceInfo.

components/browser_sync/profile_sync_components_factory_impl.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_components_factory_impl.h"
 
 #include <utility>
 
 #include "base/command_line.h"
+#include "base/debug/dump_without_crashing.h"
 #include "base/feature_list.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
 #include "build/build_config.h"
 #include "components/autofill/core/browser/autofill_wallet_data_type_controller.h"
 #include "components/autofill/core/browser/webdata/autofill_data_type_controller.h"
 #include "components/autofill/core/browser/webdata/autofill_profile_data_type_controller.h"
 #include "components/autofill/core/browser/webdata/autofill_webdata_service.h"
 #include "components/autofill/core/common/autofill_pref_names.h"
 #include "components/autofill/core/common/autofill_switches.h"
@@ skipping 119 matching lines @@
 
 void ProfileSyncComponentsFactoryImpl::RegisterCommonDataTypes(
     sync_driver::SyncService* sync_service,
     syncer::ModelTypeSet disabled_types,
     syncer::ModelTypeSet enabled_types) {
   base::Closure error_callback =
       base::Bind(&ChromeReportUnrecoverableError, channel_);
 
   // TODO(stanisc): can DEVICE_INFO be one of disabled datatypes?
   if (base::FeatureList::IsEnabled(switches::kSyncUSSDeviceInfo)) {
+    // Use an error callback that always uploads a stacktrace if it can to help
+    // get USS as stable as possible.
     sync_service->RegisterDataTypeController(
-        base::MakeUnique<UIModelTypeController>(syncer::DEVICE_INFO,
-                                                error_callback, sync_client_));
+        base::MakeUnique<UIModelTypeController>(
+            syncer::DEVICE_INFO, base::Bind(&base::debug::DumpWithoutCrashing),

[skym, 2016/09/27 23:22:39]

Hmm I was more thinking that we'd control the % with a finch param.

[maxbogue, 2016/09/27 23:37:33]

I think this is more something we'll want to have for a little while during the
rollout and then switch back as soon as we're confident there aren't many
crashes.

+            sync_client_));
   } else {
     sync_service->RegisterDataTypeController(
         base::MakeUnique<DeviceInfoDataTypeController>(
             error_callback, sync_client_,
             sync_service->GetLocalDeviceInfoProvider()));
   }
 
   // Autofill sync is enabled by default.  Register unless explicitly
   // disabled.
   if (!disabled_types.Has(syncer::AUTOFILL)) {
@@ skipping 253 matching lines @@
 
 // static
 void ProfileSyncComponentsFactoryImpl::OverridePrefsForUssTest(bool use_uss) {
   override_prefs_controller_to_uss_for_test_ = use_uss;
 }
 
 bool ProfileSyncComponentsFactoryImpl::
     override_prefs_controller_to_uss_for_test_ = false;
 
 }  // namespace browser_sync