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

content/browser/gpu/gpu_process_host.cc

Index: content/browser/gpu/gpu_process_host.cc
diff --git a/content/browser/gpu/gpu_process_host.cc b/content/browser/gpu/gpu_process_host.cc
index 8a43d7c8b99a223f30bdf341693c5d495cb5fa84..dc2707091adb658ea7ec34b7cd7860bf8a2a3404 100644
--- a/content/browser/gpu/gpu_process_host.cc
+++ b/content/browser/gpu/gpu_process_host.cc
@@ -558,9 +558,10 @@
 
   DCHECK(!mojo_child_connection_);
   mojo_child_connection_.reset(new MojoChildConnection(
-      kGpuMojoApplicationName, "", child_token_,
-      MojoShellContext::GetConnectorForIOThread(),
-      BrowserThread::GetMessageLoopProxyForThread(BrowserThread::IO)));
+      kGpuMojoApplicationName,
+      "",
+      child_token_,
+      MojoShellContext::GetConnectorForIOThread()));
 
   gpu::GpuPreferences gpu_preferences = GetGpuPreferencesFromCommandLine();
   if (in_process_) {
@@ -931,11 +932,11 @@
 }
 
 shell::InterfaceRegistry* GpuProcessHost::GetInterfaceRegistry() {
-  return mojo_child_connection_->GetInterfaceRegistry();
+  return mojo_child_connection_->connection()->GetInterfaceRegistry();
 }
 
 shell::InterfaceProvider* GpuProcessHost::GetRemoteInterfaces() {
-  return mojo_child_connection_->GetRemoteInterfaces();
+  return mojo_child_connection_->connection()->GetRemoteInterfaces();
 }
 
 GpuProcessHost::GpuProcessKind GpuProcessHost::kind() {