ipc: Allow attachment brokering for shared memory handles.

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 5afd7fa593cc51ea1b378c2f1bcebab26c30d002..39c4ef78c7fa2e62315b1252de7b8b35c44e80ce 100644
--- a/ipc/handle_attachment_win.cc
+++ b/ipc/handle_attachment_win.cc
@@ -11,18 +11,24 @@ namespace internal {
 
 HandleAttachmentWin::HandleAttachmentWin(const HANDLE& handle,
                                          HandleWin::Permissions permissions)
-    : handle_(handle), permissions_(permissions), owns_handle_(true) {}
+    : handle_(INVALID_HANDLE_VALUE),
+      permissions_(HandleWin::INVALID),
+      owns_handle_(true) {
+  HANDLE duplicated_handle;
+  BOOL result =
+      ::DuplicateHandle(GetCurrentProcess(), handle, GetCurrentProcess(),
+                        &duplicated_handle, 0, FALSE, DUPLICATE_SAME_ACCESS);
+  if (result) {
+    handle_ = duplicated_handle;
+    permissions_ = permissions;
+  }
+}
 
 HandleAttachmentWin::HandleAttachmentWin(const WireFormat& wire_format)
     : BrokerableAttachment(wire_format.attachment_id),
       handle_(LongToHandle(wire_format.handle)),
-      permissions_(wire_format.permissions), owns_handle_(false) {}
-
-HandleAttachmentWin::HandleAttachmentWin(
-    const BrokerableAttachment::AttachmentId& id)
-    : BrokerableAttachment(id),
-      handle_(INVALID_HANDLE_VALUE),
-      permissions_(HandleWin::INVALID), owns_handle_(false) {}
+      permissions_(wire_format.permissions),
+      owns_handle_(true) {}
 
 HandleAttachmentWin::~HandleAttachmentWin() {
   if (handle_ != INVALID_HANDLE_VALUE && owns_handle_)