Allow ChildThreadImpl subclasses to manually start MojoShellConnection

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index ef0fc88578b617fbc489495c12c427ec9c98fc66..72e6cc38503365ce9a66523e341dca164c49852c 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -611,6 +611,7 @@ RenderThreadImpl::RenderThreadImpl(
     : ChildThreadImpl(Options::Builder()
                           .InBrowserProcess(params)
                           .UseMojoChannel(true)
+                          .AutoStartMojoShellConnection(false)
                           .Build()),
       renderer_scheduler_(std::move(scheduler)),
       categorized_worker_pool_(new CategorizedWorkerPool()) {
@@ -622,7 +623,10 @@ RenderThreadImpl::RenderThreadImpl(
 RenderThreadImpl::RenderThreadImpl(
     std::unique_ptr<base::MessageLoop> main_message_loop,
     std::unique_ptr<scheduler::RendererScheduler> scheduler)
-    : ChildThreadImpl(Options::Builder().UseMojoChannel(true).Build()),
+    : ChildThreadImpl(Options::Builder()
+                          .UseMojoChannel(true)
+                          .AutoStartMojoShellConnection(false)
+                          .Build()),
       renderer_scheduler_(std::move(scheduler)),
       main_message_loop_(std::move(main_message_loop)),
       categorized_worker_pool_(new CategorizedWorkerPool()) {
@@ -726,6 +730,16 @@ void RenderThreadImpl::Init(
 
   AddFilter((new ServiceWorkerContextMessageFilter())->GetFilter());
 
+#if defined(MOJO_SHELL_CLIENT) && defined(USE_AURA)
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kUseMusInRenderer)) {
+    CreateRenderWidgetWindowTreeClientFactory(GetMojoShellConnection());
+  }
+#endif
+
+  // Must be called before RenderThreadStarted() below.
+  StartMojoShellConnection();
+
   GetContentClient()->renderer()->RenderThreadStarted();
 
   InitSkiaEventTracer();
@@ -987,15 +1001,6 @@ void RenderThreadImpl::Shutdown() {
   lazy_tls.Pointer()->Set(nullptr);
 }
 
-void RenderThreadImpl::AddConnectionFilters(MojoShellConnection* connection) {
-#if defined(MOJO_SHELL_CLIENT) && defined(USE_AURA)
-  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kUseMusInRenderer)) {
-    CreateRenderWidgetWindowTreeClientFactory(connection);
-  }
-#endif
-}
-
 bool RenderThreadImpl::Send(IPC::Message* msg) {
   // There are cases where we want to pump asynchronous messages while waiting
   // synchronously for the replies to the message to be sent here. However, this