Moves OSExchangeDataProviderMus to aura/mus

ui/views/mus/drag_drop_client_mus.cc

Index: ui/views/mus/drag_drop_client_mus.cc
diff --git a/ui/views/mus/drag_drop_client_mus.cc b/ui/views/mus/drag_drop_client_mus.cc
index d4d65cf9fbfd321b8de1fe964c55801d352b5ae6..308973967ce455534d280a63236380e1f88803a9 100644
--- a/ui/views/mus/drag_drop_client_mus.cc
+++ b/ui/views/mus/drag_drop_client_mus.cc
@@ -11,8 +11,8 @@
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "services/ui/public/cpp/window.h"
+#include "ui/aura/mus/os_exchange_data_provider_mus.h"
 #include "ui/aura/window.h"
-#include "ui/views/mus/os_exchange_data_provider_mus.h"
 
 namespace views {
 namespace {
@@ -34,7 +34,8 @@ int DragDropClientMus::StartDragAndDrop(
     int drag_operations,
     ui::DragDropTypes::DragEventSource source) {
   std::map<std::string, std::vector<uint8_t>> drag_data =
-      static_cast<const OSExchangeDataProviderMus&>(data.provider()).GetData();
+      static_cast<const aura::OSExchangeDataProviderMus&>(data.provider())
+          .GetData();
 
   // TODO(erg): Right now, I'm passing the cursor_location, but maybe I want to
   // pass OSExchangeData::GetDragImageOffset() instead?