Allow OSExchangeData::Provider to be overridden at run time.

ui/base/dragdrop/os_exchange_data_provider_builder_mac.mm

Index: ui/base/dragdrop/os_exchange_data_provider_builder_mac.mm
diff --git a/ui/base/dragdrop/os_exchange_data_provider_builder_mac.mm b/ui/base/dragdrop/os_exchange_data_provider_builder_mac.mm
new file mode 100644
index 0000000000000000000000000000000000000000..ccd3a00b3fb50995bede629abd2509de3981af53
--- /dev/null
+++ b/ui/base/dragdrop/os_exchange_data_provider_builder_mac.mm
@@ -0,0 +1,15 @@
+// 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 "ui/base/dragdrop/os_exchange_data_provider_builder_mac.h"
+
+#include "ui/base/dragdrop/os_exchange_data_provider_mac.h"
+
+namespace ui {
+
+OSExchangeData::Provider* BuildOSExchangeDataProviderMac() {
+  return new OSExchangeDataProviderMac();
+}
+
+}  // namespace ui