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

chrome/test/base/mash_browser_tests_main.cc

Index: chrome/test/base/mash_browser_tests_main.cc
diff --git a/chrome/test/base/mash_browser_tests_main.cc b/chrome/test/base/mash_browser_tests_main.cc
index 30112bd5f13fafbed1258f44219135f2101d0007..6dea6adc9a2ad29b0e196963bfd045d51fceb16c 100644
--- a/chrome/test/base/mash_browser_tests_main.cc
+++ b/chrome/test/base/mash_browser_tests_main.cc
@@ -10,7 +10,6 @@
 #include "base/memory/ptr_util.h"
 #include "base/process/launch.h"
 #include "base/sys_info.h"
-#include "base/threading/thread_task_runner_handle.h"
 #include "chrome/test/base/chrome_test_launcher.h"
 #include "chrome/test/base/chrome_test_suite.h"
 #include "chrome/test/base/mojo_test_connector.h"
@@ -109,9 +108,7 @@
     MashTestLauncherDelegate* delegate) {
   std::unique_ptr<content::MojoShellConnection> connection(
       content::MojoShellConnection::Create(
-          delegate->GetMojoTestConnectorForSingleProcess()->Init(),
-          base::ThreadTaskRunnerHandle::Get()));
-  connection->Start();
+          delegate->GetMojoTestConnectorForSingleProcess()->Init()));
   ConnectToDefaultApps(connection->GetConnector());
   return connection;
 }