Add member ownership_passes_to_ipc_ to SharedMemoryHandle on windows.

Prior to attachment brokering, the semantics for SharedMemoryHandle differed
between Windows and other platforms. On other platforms, if a handle is passed
to the IPC stack, there is a flag that indicates whether ownership also passed.
On Windows, there was no flag, and whether ownership was passed, or leaked
(waiting for another process to close it), was entirely context dependent.
Adding this flag to attachment-brokered SharedMemoryHandles on Windows mean that
they now have the same ownership semantics as SharedMemoryHandles on other
platforms.

BUG=580636

Review URL: https://codereview.chromium.org/1643253003

Cr-Commit-Position: refs/heads/master@{#372783}

1 files changed, 5 insertions, 0 deletions

diff --git a/ipc/ipc_message_utils.cc b/ipc/ipc_message_utils.cc
index ea88b55..277c2ff 100644
--- a/ipc/ipc_message_utils.cc
+++ b/ipc/ipc_message_utils.cc
@@ -665,6 +665,11 @@ void ParamTraits<base::SharedMemoryHandle>::Write(Message* m,
   if (p.NeedsBrokering()) {
     HandleWin handle_win(p.GetHandle(), HandleWin::DUPLICATE);
     ParamTraits<HandleWin>::Write(m, handle_win);
+
+    // If the caller intended to pass ownership to the IPC stack, release a
+    // reference.
+    if (p.OwnershipPassesToIPC())
+      p.Close();
   } else {
     m->WriteInt(HandleToLong(p.GetHandle()));
   }