Mojo EDK: Add safe process connection API

remoting/host/win/unprivileged_process_delegate.cc

Index: remoting/host/win/unprivileged_process_delegate.cc
diff --git a/remoting/host/win/unprivileged_process_delegate.cc b/remoting/host/win/unprivileged_process_delegate.cc
index c9f00415107d6b597d39c84d6c03217fd19a321b..5c0a6b54d8703ca351b8c0460b605d9605b3a1e7 100644
--- a/remoting/host/win/unprivileged_process_delegate.cc
+++ b/remoting/host/win/unprivileged_process_delegate.cc
@@ -26,6 +26,7 @@
 #include "ipc/ipc_channel_proxy.h"
 #include "ipc/ipc_message.h"
 #include "mojo/edk/embedder/embedder.h"
+#include "mojo/edk/embedder/pending_process_connection.h"
 #include "mojo/edk/embedder/platform_channel_pair.h"
 #include "remoting/base/typed_buffer.h"
 #include "remoting/host/switches.h"
@@ -283,13 +284,10 @@ void UnprivilegedProcessDelegate::LaunchProcess(
     return;
   }
 
-  const std::string mojo_child_token = mojo::edk::GenerateRandomToken();
-  const std::string mojo_message_pipe_token = mojo::edk::GenerateRandomToken();
-
+  mojo::edk::PendingProcessConnection process;
+  std::string mojo_message_pipe_token;
   std::unique_ptr<IPC::ChannelProxy> server = IPC::ChannelProxy::Create(
-      mojo::edk::CreateParentMessagePipe(mojo_message_pipe_token,
-                                         mojo_child_token)
-          .release(),
+      process.CreateMessagePipe(&mojo_message_pipe_token).release(),
       IPC::Channel::MODE_SERVER, this, io_task_runner_);
   base::CommandLine command_line(target_command_->argv());
   command_line.AppendSwitchASCII(kMojoPipeToken, mojo_message_pipe_token);
@@ -310,12 +308,10 @@ void UnprivilegedProcessDelegate::LaunchProcess(
           token.Get(), &process_attributes, &thread_attributes,
           handles_to_inherit, /* creation_flags= */ 0,
           /* thread_attributes= */ nullptr, &worker_process, &worker_thread)) {
-    mojo::edk::ChildProcessLaunchFailed(mojo_child_token);
     ReportFatalError();
     return;
   }
-  mojo::edk::ChildProcessLaunched(
-      worker_process.Get(), mojo_channel.PassServerHandle(), mojo_child_token);
+  process.Connect(worker_process.Get(), mojo_channel.PassServerHandle());
 
   channel_ = std::move(server);