Add an Ioctl() message to the File interface.

services/files/file_impl.h

Index: services/files/file_impl.h
diff --git a/services/files/file_impl.h b/services/files/file_impl.h
index 3c70c11831ea0dfadafa788260873fd38fb8fcb7..58fa94cca4648964f1ab98ce15496a621f14b285 100644
--- a/services/files/file_impl.h
+++ b/services/files/file_impl.h
@@ -53,6 +53,9 @@ class FileImpl : public File {
               uint32_t open_flags,
               const ReopenCallback& callback) override;
   void AsBuffer(const AsBufferCallback& callback) override;
+  void Ioctl(uint32_t request,
+             Array<uint32_t> in_values,
+             const IoctlCallback& callback);
 
  private:
   StrongBinding<File> binding_;