Revert of [mojo-edk] Simplify multiprocess pipe bootstrap (patchset #7 id:140001 of https://codereview.chromium.org/1675603002/ )

Reason for revert:
This patch broke several browsertests on Linux: PlatformAppBrowserTest.LoadAndLaunchAppChromeRunning, PlatformAppBrowserTest.LoadAndLaunchAppWithFile, PolicyMakeDefaultBrowserTest.MakeDefaultDisabled (e.g., https://build.chromium.org/p/chromium.linux/buildstatus?builder=Linux%20Tests%20%28dbg%29%281%29%2832%29&number=25685). I could repro the failures locally, and reverting this patch fixed them.

Example failure:

PlatformAppBrowserTest.LoadAndLaunchAppChromeRunning (run #1):
[ RUN      ] PlatformAppBrowserTest.LoadAndLaunchAppChromeRunning
<snip>
[26865:26901:0209/004101:FATAL:thread.cc(270)] Check failed: GetThreadWasQuitProperly().
#0 0x0000f7142d94 base::debug::StackTrace::StackTrace()
#1 0x0000f71a998f logging::LogMessage::~LogMessage()
#2 0x0000f72cc94f base::Thread::ThreadMain()
#3 0x0000f72b487a base::(anonymous namespace)::ThreadFunc()
#4 0x0000e749dd4c start_thread
#5 0x0000e6a7cb8e clone

Original issue's description:
> [mojo-edk] Simplify multiprocess pipe bootstrap
>
> This introduces a new MergePort message at the Ports layer
> for joining two independent port cycles which each have
> an unused (i.e. unwritten, unread, unsent) receiving port.
>
> MergePort allows us to create a MessagePipeDispatcher which
> is immediately usable but which will eventually be linked to
> a MessagePipeDispatcher on another port cycle, potentially in
> another process.
>
> The basic idea is to create a fully functional port pair but
> only bind one port to an MPD. Do this on each end and
> merge the dangling ports asynchronously.
>
> The simplification here allows a lot of code to be deleted
> from NodeController, some of which is deleted in this CL.
>
> Future work will convert existing bootstrap sites back to
> using synchronous bootstrap, including the token-based APIs.
>
> BUG=584764
> TBR=ben@chromium.org for null check in mash shell
>
> Committed: https://crrev.com/b3ea203171e07f5c7e476e94d210ec4ad53ce5b0
> Cr-Commit-Position: refs/heads/master@{#374322}

TBR=amistry@chromium.org,darin@chormium.org,rockot@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=584764

Review URL: https://codereview.chromium.org/1678333003

Cr-Commit-Position: refs/heads/master@{#374346}

1 files changed, 10 insertions, 13 deletions

diff --git a/mojo/edk/system/remote_message_pipe_bootstrap.cc b/mojo/edk/system/remote_message_pipe_bootstrap.cc
index 2342166..671542f3 100644
--- a/mojo/edk/system/remote_message_pipe_bootstrap.cc
+++ b/mojo/edk/system/remote_message_pipe_bootstrap.cc
@@ -31,17 +31,18 @@ struct BootstrapData {
 void RemoteMessagePipeBootstrap::Create(
     NodeController* node_controller,
     ScopedPlatformHandle platform_handle,
-    const ports::PortRef& port) {
+    const ports::PortRef& port,
+    const base::Closure& callback) {
   if (node_controller->io_task_runner()->RunsTasksOnCurrentThread()) {
     // Owns itself.
-    new RemoteMessagePipeBootstrap(
-        node_controller, std::move(platform_handle), port);
+    new RemoteMessagePipeBootstrap(node_controller, std::move(platform_handle),
+                                   port, callback);
   } else {
     node_controller->io_task_runner()->PostTask(
         FROM_HERE,
         base::Bind(&RemoteMessagePipeBootstrap::Create,
                    base::Unretained(node_controller),
-                   base::Passed(&platform_handle), port));
+                   base::Passed(&platform_handle), port, callback));
   }
 }
 
@@ -55,9 +56,11 @@ RemoteMessagePipeBootstrap::~RemoteMessagePipeBootstrap() {
 RemoteMessagePipeBootstrap::RemoteMessagePipeBootstrap(
     NodeController* node_controller,
     ScopedPlatformHandle platform_handle,
-    const ports::PortRef& port)
+    const ports::PortRef& port,
+    const base::Closure& callback)
     : node_controller_(node_controller),
       local_port_(port),
+      callback_(callback),
       io_task_runner_(base::ThreadTaskRunnerHandle::Get()),
       channel_(Channel::Create(this, std::move(platform_handle),
                                io_task_runner_)) {
@@ -116,14 +119,8 @@ void RemoteMessagePipeBootstrap::OnChannelMessage(
   }
 
   peer_info_received_ = true;
-
-  // We need to choose one side to initiate the port merge. It doesn't matter
-  // who does it as long as they don't both try. Simple solution: pick the one
-  // with the "smaller" port name.
-  if (local_port_.name() < data->port_name) {
-    node_controller_->node()->MergePorts(local_port_, data->node_name,
-                                         data->port_name);
-  }
+  node_controller_->ConnectToRemotePort(
+      local_port_, data->node_name, data->port_name, callback_);
 
   // Send another ping to the other end to trigger shutdown. This may race with
   // the other end sending its own ping, but it doesn't matter. Whoever wins