ChromeOS: Fix DCHECK failure after file copying in Drive folder.

chrome/browser/chromeos/gdata/gdata_file_system.cc

 // Copyright (c) 2012 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/gdata/gdata_file_system.h"
 
 #include <set>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 3065 matching lines @@
                             base::Bind(&OnCacheUpdatedForAddUploadedFile,
                                        params->callback));
   } else if (params->upload_mode == UPLOAD_EXISTING_FILE) {
     // Clear the dirty bit if we have updated an existing file.
     cache_->ClearDirtyOnUIThread(params->resource_id,
                                  params->md5,
                                  base::Bind(&OnCacheUpdatedForAddUploadedFile,
                                             params->callback));
   } else {
     NOTREACHED() << "Unexpected upload mode: " << params->upload_mode;
+    // Shouldn't reach here, so the line below should not make much sense, but
+    // since calling |callback| exactly once is our obligation, we'd better call
+    // it for not to clutter further more.
+    params->callback.Run();
   }
-  params->callback.Run();
 }
 
 void GDataFileSystem::Observe(int type,
                               const content::NotificationSource& source,
                               const content::NotificationDetails& details) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   if (type == chrome::NOTIFICATION_PREF_CHANGED) {
     PrefService* pref_service = profile_->GetPrefs();
     std::string* pref_name = content::Details<std::string>(details).ptr();
@@ skipping 353 matching lines @@
     return;
   }
 
   PlatformFileInfoProto entry_file_info;
   GDataEntry::ConvertPlatformFileInfoToProto(*file_info, &entry_file_info);
   *entry_proto->mutable_file_info() = entry_file_info;
   callback.Run(GDATA_FILE_OK, entry_proto.Pass());
 }
 
 }  // namespace gdata