Files.app: Fix a call of the default task picker.

chrome/browser/chromeos/extensions/file_manager/private_api_tasks.cc

 // Copyright 2013 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 "chrome/browser/chromeos/extensions/file_manager/private_api_tasks.h"
 
 #include "chrome/browser/chromeos/drive/file_system_util.h"
 #include "chrome/browser/chromeos/extensions/file_manager/private_api_util.h"
 #include "chrome/browser/chromeos/file_manager/file_tasks.h"
 #include "chrome/browser/chromeos/file_manager/fileapi_util.h"
@@ skipping 29 matching lines @@
       suffixes.insert(url.path().Extension());
   }
   return suffixes;
 }
 
 // Make a set of unique MIME types out of the list of MIME types.
 std::set<std::string> GetUniqueMimeTypes(
     const std::vector<std::string>& mime_type_list) {
   std::set<std::string> mime_types;
   for (size_t i = 0; i < mime_type_list.size(); ++i) {
-    std::string mime_type;
-    // We'll skip empty MIME types.
+    const std::string mime_type = mime_type_list[i];
+    // We'll skip empty MIME types and existing MIME types.
     if (!mime_type.empty())
       mime_types.insert(mime_type);
   }
   return mime_types;
 }
 
 }  // namespace
 
 bool FileBrowserPrivateExecuteTaskFunction::RunImpl() {
   using extensions::api::file_browser_private::ExecuteTask::Params;
@@ skipping 141 matching lines @@
     SetResult(new base::FundamentalValue(true));
     return true;
   }
 
   file_manager::file_tasks::UpdateDefaultTask(
       GetProfile()->GetPrefs(), params->task_id, suffixes, mime_types);
   return true;
 }
 
 }  // namespace extensions