ipc: Move //crypto dependency into a Windows-only file.

ipc/handle_attachment_win.cc

Index: ipc/handle_attachment_win.cc
diff --git a/ipc/handle_attachment_win.cc b/ipc/handle_attachment_win.cc
index 429c964ee53312bb443491e0f25b410889389df3..50e3e6dab24310c5bba54d5f44cfa42cb436630e 100644
--- a/ipc/handle_attachment_win.cc
+++ b/ipc/handle_attachment_win.cc
@@ -6,29 +6,12 @@
 
 #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)
-    : BrokerableAttachment(GenerateAttachementId(), true),
-      handle_(handle),
-      permissions_(permissions) {}
+    : handle_(handle), permissions_(permissions) {}
 
 HandleAttachmentWin::HandleAttachmentWin(const WireFormat& wire_format)
     : BrokerableAttachment(wire_format.attachment_id, false),