Remove dependency on //crypto in //ipc, except on windows.

ipc/handle_attachment_win.cc

 // Copyright 2015 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 "ipc/handle_attachment_win.h"
 
 #include <windows.h>
 
+#include "crypto/random.h"
+
 namespace IPC {
 namespace internal {
 
+namespace {
+
+// In order to prevent mutually untrusted processes from stealing resources from
+// one another, the nonce must be secret. This generates a 128-bit,
+// cryptographicaly-strong random number.
+BrokerableAttachment::AttachmentId GenerateAttachementId() {
+  BrokerableAttachment::AttachmentId result;
+  crypto::RandBytes(result.nonce, BrokerableAttachment::kNonceSize);
+  return result;
+}
+
+}  // namespace
+
 HandleAttachmentWin::HandleAttachmentWin(const HANDLE& handle,
                                          HandleWin::Permissions permissions)
-    : handle_(handle), permissions_(permissions) {}
+    : BrokerableAttachment(GenerateAttachementId(), true),
+      handle_(handle),
+      permissions_(permissions) {}
 
 HandleAttachmentWin::HandleAttachmentWin(const WireFormat& wire_format)
     : BrokerableAttachment(wire_format.attachment_id, false),
       handle_(LongToHandle(wire_format.handle)),
       permissions_(wire_format.permissions) {}
 
 HandleAttachmentWin::HandleAttachmentWin(
     const BrokerableAttachment::AttachmentId& id)
     : BrokerableAttachment(id, true),
       handle_(INVALID_HANDLE_VALUE),
@@ skipping 25 matching lines @@
   WireFormat format;
   format.handle = HandleToLong(handle_);
   format.attachment_id = GetIdentifier();
   format.destination_process = destination;
   format.permissions = permissions_;
   return format;
 }
 
 }  // namespace internal
 }  // namespace IPC