Fix flaky PPAPITest.FileIO_NotAllowMixedReadWrite, re-enable

ppapi/tests/test_file_io.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 "ppapi/tests/test_file_io.h"
 
 #include <string.h>
 
 #include <vector>
 
@@ skipping 884 matching lines @@
   int32_t read_offset_2 = 4;
   char buf_2[3];
   int32_t rv_2 = file_io.Read(read_offset_2, buf_2, sizeof(buf_2),
                               callback_2);
   if (force_async_ && rv_2 != PP_OK_COMPLETIONPENDING)
     return ReportError("FileIO::Read force_async", rv_2);
   if (rv_2 == PP_OK_COMPLETIONPENDING)
     rv_2 = callback_2.WaitForResult();
   if (rv_2 != PP_ERROR_INPROGRESS)
     return ReportError("FileIO::Read", rv_2);
+  callback_1.WaitForResult();
 
-  // Cannot query while the write is pending.
+  // Cannot query while a write is pending.
+  rv_1 = file_io.Write(write_offset_1, buf_1, strlen(buf_1), callback_1);
+  ASSERT_EQ(PP_OK_COMPLETIONPENDING, rv_1);
   TestCompletionCallback callback_3(instance_->pp_instance(), force_async_);
   PP_FileInfo info;
   int32_t rv_3 = file_io.Query(&info, callback_3);
   if (rv_3 == PP_OK_COMPLETIONPENDING)
     rv_3 = callback_3.WaitForResult();
   if (rv_3 != PP_ERROR_INPROGRESS)
     return ReportError("FileIO::Query", rv_3);
+  callback_1.WaitForResult();
 
-  // Cannot touch while the write is pending.
+  // Cannot touch while a write is pending.
+  rv_1 = file_io.Write(write_offset_1, buf_1, strlen(buf_1), callback_1);
+  ASSERT_EQ(PP_OK_COMPLETIONPENDING, rv_1);
   TestCompletionCallback callback_4(instance_->pp_instance(), force_async_);
   int32_t rv_4 = file_io.Touch(1234.0, 5678.0, callback_4);
   if (rv_4 == PP_OK_COMPLETIONPENDING)
     rv_4 = callback_4.WaitForResult();
   if (rv_4 != PP_ERROR_INPROGRESS)
     return ReportError("FileIO::Touch", rv_4);
+  callback_1.WaitForResult();
 
-  // Cannot set length while the write is pending.
+  // Cannot set length while a write is pending.
+  rv_1 = file_io.Write(write_offset_1, buf_1, strlen(buf_1), callback_1);
+  ASSERT_EQ(PP_OK_COMPLETIONPENDING, rv_1);
   TestCompletionCallback callback_5(instance_->pp_instance(), force_async_);
   int32_t rv_5 = file_io.SetLength(123, callback_5);
   if (rv_5 == PP_OK_COMPLETIONPENDING)
     rv_5 = callback_5.WaitForResult();
   if (rv_5 != PP_ERROR_INPROGRESS)
     return ReportError("FileIO::SetLength", rv_5);
-
   callback_1.WaitForResult();
 
   PASS();
 }
 
 std::string TestFileIO::TestWillWriteWillSetLength() {
   TestCompletionCallback callback(instance_->pp_instance(), force_async_);
 
   pp::FileSystem file_system(instance_, PP_FILESYSTEMTYPE_LOCALTEMPORARY);
   pp::FileRef file_ref(file_system, "/file_will_write");
@@ skipping 178 matching lines @@
     rv = callback.WaitForResult();
   if ((invalid_combination && rv == PP_OK) ||
       (!invalid_combination && ((rv == PP_OK) != create_if_doesnt_exist))) {
     return ReportOpenError(open_flags);
   }
 
   return std::string();
 }
 
 // TODO(viettrungluu): Test Close(). crbug.com/69457