Add support for Attachment Brokering of IPC::Channels on multiple threads.

ipc/attachment_broker_privileged_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/attachment_broker_privileged_win.h"
 
 #include <windows.h>
 
 #include <tuple>
 
@@ skipping 68 matching lines @@
   if (wire_format.destination_process == base::Process::Current().Pid()) {
     scoped_refptr<BrokerableAttachment> attachment(
         new internal::HandleAttachmentWin(wire_format));
     HandleReceivedAttachment(attachment);
     return;
   }
 
   // Another process is the destination.
   base::ProcessId dest = wire_format.destination_process;
   base::AutoLock auto_lock(*get_lock());
-  Sender* sender = GetSenderWithProcessId(dest);
-  if (!sender) {
+  AttachmentBrokerPrivileged::EndpointRunnerPair pair =
+      GetSenderWithProcessId(dest);
+  if (!pair.first) {
     // Assuming that this message was not sent from a malicious process, the
     // channel endpoint that would have received this message will block
     // forever.
     LOG(ERROR) << "Failed to deliver brokerable attachment to process with id: "
                << dest;
     LogError(DESTINATION_NOT_FOUND);
     return;
   }
 
   LogError(DESTINATION_FOUND);
-  sender->Send(new AttachmentBrokerMsg_WinHandleHasBeenDuplicated(wire_format));
+  SendMessageToEndpoint(
+      pair, new AttachmentBrokerMsg_WinHandleHasBeenDuplicated(wire_format));
 }
 
 AttachmentBrokerPrivilegedWin::HandleWireFormat
 AttachmentBrokerPrivilegedWin::DuplicateWinHandle(
     const HandleWireFormat& wire_format,
     base::ProcessId source_pid) {
   // If the source process is the destination process, then no additional work
   // is required.
   if (source_pid == wire_format.destination_process)
     return wire_format;
@@ skipping 37 matching lines @@
 
 AttachmentBrokerPrivilegedWin::HandleWireFormat
 AttachmentBrokerPrivilegedWin::CopyWireFormat(
     const HandleWireFormat& wire_format,
     int handle) {
   return HandleWireFormat(handle, wire_format.destination_process,
                           wire_format.permissions, wire_format.attachment_id);
 }
 
 }  // namespace IPC