Revert of Move content's shell connections to the IO thread

content/browser/browser_context.cc

 // Copyright (c) 2012 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 "content/public/browser/browser_context.h"
 
 #include <stddef.h>
 #include <stdint.h>
 #include <algorithm>
 #include <limits>
@@ skipping 134 matching lines @@
   context->SetUserData(kDownloadManagerKeyName, download_manager);
 }
 
 class BrowserContextShellConnectionHolder
     : public base::SupportsUserData::Data {
  public:
   BrowserContextShellConnectionHolder(
       std::unique_ptr<shell::Connection> connection,
       shell::mojom::ServiceRequest request)
       : root_connection_(std::move(connection)),
-        shell_connection_(MojoShellConnection::Create(
-            std::move(request),
-            BrowserThread::GetTaskRunnerForThread(BrowserThread::IO))) {}
+        shell_connection_(MojoShellConnection::Create(std::move(request))) {}
   ~BrowserContextShellConnectionHolder() override {}
 
   MojoShellConnection* shell_connection() { return shell_connection_.get(); }
 
  private:
   std::unique_ptr<shell::Connection> root_connection_;
   std::unique_ptr<MojoShellConnection> shell_connection_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserContextShellConnectionHolder);
 };
@@ skipping 260 matching lines @@
                                          mojo::GetProxy(&pid_receiver));
     pid_receiver->SetPID(base::GetCurrentProcId());
 
     BrowserContextShellConnectionHolder* connection_holder =
         new BrowserContextShellConnectionHolder(
           shell->GetConnector()->Connect(&params),
           std::move(service_request));
     browser_context->SetUserData(kMojoShellConnection, connection_holder);
 
     MojoShellConnection* connection = connection_holder->shell_connection();
-    connection->Start();
 
     // New embedded service factories should be added to |connection| here.
 
     if (base::CommandLine::ForCurrentProcess()->HasSwitch(
             switches::kMojoLocalStorage)) {
       MojoApplicationInfo info;
       info.application_factory =
           base::Bind(&user_service::CreateUserService,
                      BrowserThread::GetTaskRunnerForThread(BrowserThread::FILE),
                      BrowserThread::GetTaskRunnerForThread(BrowserThread::DB));
@@ skipping 37 matching lines @@
       << "Attempting to destroy a BrowserContext that never called "
       << "Initialize()";
 
   RemoveBrowserContextFromUserIdMap(this);
 
   if (GetUserData(kDownloadManagerKeyName))
     GetDownloadManager(this)->Shutdown();
 }
 
 }  // namespace content