Query the existence other forms of browsing history.

sync/protocol/history_status.proto

Index: sync/protocol/history_status.proto
diff --git a/sync/protocol/history_status.proto b/sync/protocol/history_status.proto
new file mode 100644
index 0000000000000000000000000000000000000000..506c4ea33ebec2526fe94c9812ed85bcac7cd436
--- /dev/null
+++ b/sync/protocol/history_status.proto
@@ -0,0 +1,23 @@
+// Copyright 2016 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
+
+syntax = "proto2";
+
+option optimize_for = LITE_RUNTIME;
+option retain_unknown_fields = true;
+
+package sync_pb;
+
+// We likely do not need this message.
+message HistoryStatusRequest {

[pavely, 2016/05/17 22:56:48]

HistoryStatusRequest is not used. Consider removing it.

[msramek, 2016/05/18 19:38:37]

Done.

kevinliu@, perhaps you want to remove it from cl/122116426 as well. There is no
data from the client to provide, so we would just send an empty POST request.

But that reminds me that I still need to set e.g. whitespace as post data,
otherwise WebHistoryService::Request will default to GET.

+}
+
+// Response to a history status request.
+message HistoryStatusResponse {
+  // Minimal time to wait before issuing another request.
+  optional int32 min_poll_interval_seconds = 1 [default = 3600];
+
+  // Indicates whether the history corpuses have any derived data for a user.
+  optional bool has_derived_data = 2;
+}