Allow ChildThreadImpl subclasses to manually start MojoShellConnection

content/child/child_thread_impl.cc

Index: content/child/child_thread_impl.cc
diff --git a/content/child/child_thread_impl.cc b/content/child/child_thread_impl.cc
index d388d33398e4003c9680ae489e28a9d01c4d774d..bfd7c6b82b014a5139dbbec13c5289650b44413f 100644
--- a/content/child/child_thread_impl.cc
+++ b/content/child/child_thread_impl.cc
@@ -265,7 +265,8 @@ ChildThreadImpl::Options::Options()
     : channel_name(base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
           switches::kProcessChannelID)),
       use_mojo_channel(base::CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kMojoChannelToken)) {
+          switches::kMojoChannelToken)),
+      auto_start_mojo_shell_connection(true) {
 }
 
 ChildThreadImpl::Options::Options(const Options& other) = default;
@@ -293,6 +294,13 @@ ChildThreadImpl::Options::Builder::UseMojoChannel(bool use_mojo_channel) {
 }
 
 ChildThreadImpl::Options::Builder&
+ChildThreadImpl::Options::Builder::AutoStartMojoShellConnection(
+    bool auto_start) {
+  options_.auto_start_mojo_shell_connection = auto_start;
+  return *this;
+}
+
+ChildThreadImpl::Options::Builder&
 ChildThreadImpl::Options::Builder::WithChannelName(
     const std::string& channel_name) {
   options_.channel_name = channel_name;
@@ -429,8 +437,8 @@ void ChildThreadImpl::Init(const Options& options) {
     mojo_shell_connection_->SetupInterfaceRequestProxies(
         GetInterfaceRegistry(), GetRemoteInterfaces());
 
-    AddConnectionFilters(mojo_shell_connection_.get());
-    mojo_shell_connection_->Start();
+    if (options.auto_start_mojo_shell_connection)
+      StartMojoShellConnection();
   }
 
   sync_message_filter_ = channel_->CreateSyncMessageFilter();
@@ -696,7 +704,10 @@ bool ChildThreadImpl::OnMessageReceived(const IPC::Message& msg) {
   return router_.OnMessageReceived(msg);
 }
 
-void ChildThreadImpl::AddConnectionFilters(MojoShellConnection* connection) {}
+void ChildThreadImpl::StartMojoShellConnection() {
+  DCHECK(mojo_shell_connection_);
+  mojo_shell_connection_->Start();
+}
 
 bool ChildThreadImpl::OnControlMessageReceived(const IPC::Message& msg) {
   return false;