Don't populate URL data in WebDropData when dragging files.

ui/base/dragdrop/os_exchange_data_provider_aura.cc

Index: ui/base/dragdrop/os_exchange_data_provider_aura.cc
diff --git a/ui/base/dragdrop/os_exchange_data_provider_aura.cc b/ui/base/dragdrop/os_exchange_data_provider_aura.cc
index bd1545d8e7e74d7cf2533e98b472f7caae6704ae..c629964df15e3af40d946ce5803c914aa65aef89 100644
--- a/ui/base/dragdrop/os_exchange_data_provider_aura.cc
+++ b/ui/base/dragdrop/os_exchange_data_provider_aura.cc
@@ -73,8 +73,11 @@ bool OSExchangeDataProviderAura::GetString(base::string16* data) const {
   return true;
 }
 
-bool OSExchangeDataProviderAura::GetURLAndTitle(GURL* url,
-                                                base::string16* title) const {
+bool OSExchangeDataProviderAura::GetURLAndTitle(
+    OSExchangeData::FilenameToURLPolicy policy,
+    GURL* url,
+    base::string16* title) const {
+  // TODO(dcheng): implement filename conversion.
   if ((formats_ & OSExchangeData::URL) == 0) {
     title->clear();
     return GetPlainTextURL(url);