Introduce ui.dll / libui.so for the component build.

ui/base/dragdrop/os_exchange_data_provider_win.h

Index: ui/base/dragdrop/os_exchange_data_provider_win.h
===================================================================
--- ui/base/dragdrop/os_exchange_data_provider_win.h	(revision 92815)
+++ ui/base/dragdrop/os_exchange_data_provider_win.h	(working copy)
@@ -11,6 +11,7 @@
 #include <string>
 
 #include "base/win/scoped_comptr.h"
+#include "ui/ui_api.h"
 #include "ui/base/dragdrop/os_exchange_data.h"
 
 namespace ui {
@@ -126,7 +127,7 @@
   Observer* observer_;
 };
 
-class OSExchangeDataProviderWin : public OSExchangeData::Provider {
+class UI_API OSExchangeDataProviderWin : public OSExchangeData::Provider {
  public:
   // Returns true if source has plain text that is a valid url.
   static bool HasPlainTextURL(IDataObject* source);