Make PlatformFileForTransit its own class on Windows.

ipc/ipc_platform_file.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 "build/build_config.h"
 #include "ipc/ipc_platform_file.h"
 
 #if defined(OS_POSIX)
 #include <unistd.h>
 #endif
 
 namespace IPC {
 
+#if defined(OS_WIN)
+PlatformFileForTransit::PlatformFileForTransit() : handle_(nullptr) {}
+
+PlatformFileForTransit::PlatformFileForTransit(HANDLE handle)
+    : handle_(handle) {}
+
+bool PlatformFileForTransit::operator==(
+    const PlatformFileForTransit& platform_file) const {
+  return handle_ == platform_file.handle_;
+}
+
+bool PlatformFileForTransit::operator!=(
+    const PlatformFileForTransit& platform_file) const {
+  return !(*this == platform_file);
+}
+
+HANDLE PlatformFileForTransit::GetHandle() const {
+  return handle_;
+}
+
+bool PlatformFileForTransit::IsValid() const {
+  return handle_ != nullptr;
+}
+
+#endif  // defined(OS_WIN)
+
 PlatformFileForTransit GetPlatformFileForTransit(base::PlatformFile handle,
                                                  bool close_source_handle) {
 #if defined(OS_WIN)
   HANDLE raw_handle = INVALID_HANDLE_VALUE;
   DWORD options = DUPLICATE_SAME_ACCESS;
   if (close_source_handle)
     options |= DUPLICATE_CLOSE_SOURCE;
   if (handle == INVALID_HANDLE_VALUE ||
       !::DuplicateHandle(::GetCurrentProcess(), handle, ::GetCurrentProcess(),
                          &raw_handle, 0, FALSE, options)) {
     return IPC::InvalidPlatformFileForTransit();
   }
 
-  IPC::PlatformFileForTransit out_handle = IPC::PlatformFileForTransit(
-      raw_handle, base::GetCurrentProcId());
-  out_handle.SetOwnershipPassesToIPC(true);
-  return out_handle;
+  return IPC::PlatformFileForTransit(raw_handle);
 #elif defined(OS_POSIX)
   // If asked to close the source, we can simply re-use the source fd instead of
   // dup()ing and close()ing.
   // When we're not closing the source, we need to duplicate the handle and take
   // ownership of that. The reason is that this function is often used to
   // generate IPC messages, and the handle must remain valid until it's sent to
   // the other process from the I/O thread. Without the dup, calling code might
   // close the source handle before the message is sent, creating a race
   // condition.
   int fd = close_source_handle ? handle : ::dup(handle);
   return base::FileDescriptor(fd, true);
 #else
   #error Not implemented.
 #endif
 }
 
 PlatformFileForTransit TakePlatformFileForTransit(base::File file) {
   return GetPlatformFileForTransit(file.TakePlatformFile(), true);
 }
 
 }  // namespace IPC