Only support seeking file streams from the beginning of the file.

chrome/browser/extensions/api/messaging/native_message_process_host_unittest.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 "base/bind.h"
 #include "base/files/file.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_file.h"
 #include "base/files/scoped_temp_dir.h"
@@ skipping 183 matching lines @@
 
 // Tests sending a single message. The message should get written to
 // |temp_file| and should match the contents of single_message_request.msg.
 TEST_F(NativeMessagingTest, SingleSendMessageWrite) {
   base::FilePath temp_output_file = temp_dir_.path().AppendASCII("output");
 
   base::File read_file;
 #if defined(OS_WIN)
   base::string16 pipe_name = base::StringPrintf(
       L"\\\\.\\pipe\\chrome.nativeMessaging.out.%llx", base::RandUint64());
-  base::File write_handle(
+  base::File write_handle = base::File::CreateForAsyncHandle(
       CreateNamedPipeW(pipe_name.c_str(),
                        PIPE_ACCESS_OUTBOUND | FILE_FLAG_OVERLAPPED |
                            FILE_FLAG_FIRST_PIPE_INSTANCE,
                        PIPE_TYPE_BYTE, 1, 0, 0, 5000, NULL));
   ASSERT_TRUE(write_handle.IsValid());
-  base::File read_handle(
+  base::File read_handle = base::File::CreateForAsyncHandle(
       CreateFileW(pipe_name.c_str(), GENERIC_READ, 0, NULL, OPEN_EXISTING,
                   FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED, NULL));
   ASSERT_TRUE(read_handle.IsValid());
 
   read_file = read_handle.Pass();
 #else  // defined(OS_WIN)
   base::PlatformFile pipe_handles[2];
   ASSERT_EQ(0, pipe(pipe_handles));
   read_file = base::File(pipe_handles[0]);
   base::File write_file(pipe_handles[1]);
@@ skipping 104 matching lines @@
   native_message_host_->Start(this);
   ASSERT_TRUE(native_message_host_.get());
   run_loop_.reset(new base::RunLoop());
   run_loop_->Run();
 
   // The host should fail to start.
   ASSERT_TRUE(channel_closed_);
 }
 
 }  // namespace extensions