Get drag and drop working for win aura.

ui/views/widget/desktop_aura/desktop_root_window_host_win.cc

Index: ui/views/widget/desktop_aura/desktop_root_window_host_win.cc
===================================================================
--- ui/views/widget/desktop_aura/desktop_root_window_host_win.cc	(revision 170738)
+++ ui/views/widget/desktop_aura/desktop_root_window_host_win.cc	(working copy)
@@ -25,8 +25,11 @@
 #include "ui/views/widget/desktop_aura/desktop_activation_client.h"
 #include "ui/views/widget/desktop_aura/desktop_cursor_client.h"
 #include "ui/views/widget/desktop_aura/desktop_dispatcher_client.h"
+#include "ui/views/widget/desktop_aura/desktop_drag_drop_client_win.h"
 #include "ui/views/widget/desktop_aura/desktop_native_widget_aura.h"
 #include "ui/views/widget/desktop_aura/desktop_screen_position_client.h"
+#include "ui/views/widget/drop_target_win.h"
+#include "ui/views/widget/root_view.h"
 #include "ui/views/widget/widget_delegate.h"
 #include "ui/views/widget/widget_hwnd_utils.h"
 #include "ui/views/win/fullscreen_handler.h"
@@ -129,11 +132,13 @@
   cursor_client_.reset(new DesktopCursorClient(root_window_));
   aura::client::SetCursorClient(root_window_, cursor_client_.get());
 
-
   position_client_.reset(new DesktopScreenPositionClient());
   aura::client::SetScreenPositionClient(root_window_,
                                         position_client_.get());
 
+  drag_drop_client_.reset(new DesktopDragDropClientWin);
+  aura::client::SetDragDropClient(root_window_, drag_drop_client_.get());
+
   // CEF sets focus to the window the user clicks down on.
   // TODO(beng): see if we can't do this some other way. CEF seems a heavy-
   //             handed way of accomplishing focus.
@@ -610,15 +615,22 @@
   // TODO(beng): moar
   NOTIMPLEMENTED();
 
+  drop_target_ = new DropTargetWin(
+      static_cast<internal::RootView*>(GetWidget()->GetRootView()),
+      GetHWND());
+
   native_widget_delegate_->OnNativeWidgetCreated();
 
   // 1. Window property association
   // 2. MouseWheel.
-  // 3. Drop target.
-  // 4. Tooltip Manager.
+  // 3. Tooltip Manager.
 }
 
 void DesktopRootWindowHostWin::HandleDestroying() {
+  if (drop_target_.get()) {
+    RevokeDragDrop(GetHWND());
+    drop_target_ = NULL;
+  }
   native_widget_delegate_->OnNativeWidgetDestroying();
 }