Pepper: Make PPB_FileChooser_Dev::Show "return" PP_ERROR_USERCANCEL if no file is selected.

webkit/plugins/ppapi/ppb_file_chooser_impl.cc

 // Copyright (c) 2011 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 "webkit/plugins/ppapi/ppb_file_chooser_impl.h"
 
 #include <string>
 #include <vector>
 
 #include "base/logging.h"
@@ skipping 126 matching lines @@
 #if defined(OS_WIN)
     FilePath file_path(base::SysUTF8ToWide(*it));
 #else
     FilePath file_path(*it);
 #endif
 
     chosen_files_.push_back(make_scoped_refptr(
         new PPB_FileRef_Impl(instance(), file_path)));
   }
 
-  RunCallback(PP_OK);
+  RunCallback((chosen_files_.size() > 0) ? PP_OK : PP_ERROR_USERCANCEL);
 }
 
 int32_t PPB_FileChooser_Impl::ValidateCallback(
     const PP_CompletionCallback& callback) {
   // We only support non-blocking calls.
   if (!callback.func)
     return PP_ERROR_BADARGUMENT;
 
   if (callback_.get() && !callback_->completed())
     return PP_ERROR_INPROGRESS;
@@ skipping 41 matching lines @@
 
 scoped_refptr<PPB_FileRef_Impl> PPB_FileChooser_Impl::GetNextChosenFile() {
   if (next_chosen_file_index_ >= chosen_files_.size())
     return NULL;
 
   return chosen_files_[next_chosen_file_index_++];
 }
 
 }  // namespace ppapi
 }  // namespace webkit