[Sync] Move GenerateSyncableHash to base.

components/sync/base/hash_util.cc

Index: components/sync/base/hash_util.cc
diff --git a/components/sync/base/hash_util.cc b/components/sync/base/hash_util.cc
new file mode 100644
index 0000000000000000000000000000000000000000..58924ff3b44f235b77883412fe66efa40812e47f
--- /dev/null
+++ b/components/sync/base/hash_util.cc
@@ -0,0 +1,35 @@
+// 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.
+
+#include "components/sync/base/hash_util.h"
+
+#include "base/base64.h"
+#include "base/sha1.h"
+#include "components/sync/protocol/sync.pb.h"
+
+namespace syncer {
+
+std::string GenerateSyncableHash(ModelType model_type,
+                                 const std::string& client_tag) {
+  // Blank PB with just the field in it has termination symbol,
+  // handy for delimiter.
+  sync_pb::EntitySpecifics serialized_type;
+  AddDefaultFieldValue(model_type, &serialized_type);
+  std::string hash_input;
+  serialized_type.AppendToString(&hash_input);
+  hash_input.append(client_tag);
+
+  std::string encode_output;
+  base::Base64Encode(base::SHA1HashString(hash_input), &encode_output);
+  return encode_output;
+}
+
+std::string GenerateSyncableBookmarkHash(
+    const std::string& originator_cache_guid,
+    const std::string& originator_client_item_id) {
+  return GenerateSyncableHash(
+      BOOKMARKS, originator_cache_guid + originator_client_item_id);
+}
+
+}  // namespace syncer