Merge definitions of PlatformFileToInt and IntToPlatformFile to one place.

ppapi/shared_impl/platform_file.cc

Index: ppapi/shared_impl/platform_file.cc
diff --git a/ppapi/shared_impl/platform_file.cc b/ppapi/shared_impl/platform_file.cc
new file mode 100644
index 0000000000000000000000000000000000000000..fe9c2ff6bd39666c6be9e1303500e02001bd5407
--- /dev/null
+++ b/ppapi/shared_impl/platform_file.cc
@@ -0,0 +1,31 @@
+// 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/shared_impl/platform_file.h"
+
+namespace ppapi {
+
+// TODO(piman/brettw): Change trusted interface to return a PP_FileHandle,
+// those casts are ugly.
+base::PlatformFile IntToPlatformFile(int32_t handle) {
+#if defined(OS_WIN)
+  return reinterpret_cast<HANDLE>(static_cast<intptr_t>(handle));
+#elif defined(OS_POSIX)
+  return handle;
+#else
+  #error Not implemented.
+#endif
+}
+
+int32_t PlatformFileToInt(base::PlatformFile handle) {
+#if defined(OS_WIN)
+  return static_cast<int32_t>(reinterpret_cast<intptr_t>(handle));
+#elif defined(OS_POSIX)
+  return handle;
+#else
+  #error Not implemented.
+#endif
+}
+
+}  // namespace ppapi