Rewrite std::string("") to std::string(), Linux edition.

chrome/browser/google_apis/drive_api_operations_unittest.cc

 // Copyright (c) 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 "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/message_loop_proxy.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/values.h"
 #include "chrome/browser/google_apis/drive_api_operations.h"
@@ skipping 849 matching lines @@
   // Initiate uploading a new file to the directory with "parent_resource_id".
   drive::InitiateUploadExistingFileOperation* operation =
       new drive::InitiateUploadExistingFileOperation(
           &operation_registry_,
           request_context_getter_.get(),
           *url_generator_,
           base::FilePath(FILE_PATH_LITERAL("drive/file/path")),
           kTestContentType,
           kTestContent.size(),
           "resource_id",  // The resource id of the file to be overwritten.
-          "",  // No etag.
+          std::string(),  // No etag.
           CreateComposedCallback(
               base::Bind(&test_util::RunAndQuit),
               test_util::CreateCopyResultCallback(&error, &upload_url)));
   operation->Start(kTestDriveApiAuthToken, kTestUserAgent,
                    base::Bind(&test_util::DoNothingForReAuthenticateCallback));
   MessageLoop::current()->Run();
 
   EXPECT_EQ(HTTP_SUCCESS, error);
   EXPECT_EQ(kTestUploadExistingFilePath, upload_url.path());
   EXPECT_EQ(kTestContentType, http_request_.headers["X-Upload-Content-Type"]);
@@ skipping 175 matching lines @@
   EXPECT_EQ("Conflicting-etag", http_request_.headers["If-Match"]);
 
   EXPECT_EQ(test_server::METHOD_PUT, http_request_.method);
   EXPECT_EQ("/upload/drive/v2/files/resource_id?uploadType=resumable",
             http_request_.relative_url);
   EXPECT_TRUE(http_request_.has_content);
   EXPECT_TRUE(http_request_.content.empty());
 }
 
 }  // namespace google_apis