[Sync] Always upload stack traces for USS DeviceInfo.

components/browser_sync/profile_sync_components_factory_impl.cc

Index: components/browser_sync/profile_sync_components_factory_impl.cc
diff --git a/components/browser_sync/profile_sync_components_factory_impl.cc b/components/browser_sync/profile_sync_components_factory_impl.cc
index d8f48377b75fa03c870c7fb4c8e71008c4e9d6b3..0f550ac9eb70b6e94cfa1a397d3c24b77b5f0e86 100644
--- a/components/browser_sync/profile_sync_components_factory_impl.cc
+++ b/components/browser_sync/profile_sync_components_factory_impl.cc
@@ -7,6 +7,7 @@
 #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"
@@ -146,9 +147,12 @@ void ProfileSyncComponentsFactoryImpl::RegisterCommonDataTypes(
 
   // 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>(