Always use ChannelMojo for content child processes.

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 b8c54bfa0b226ccb02bcc296627e70799ee8b10d..6cd69eea682b41131f420ae23dd6f10b9a8ed605 100644
--- a/content/browser/gpu/gpu_process_host.cc
+++ b/content/browser/gpu/gpu_process_host.cc
@@ -59,7 +59,6 @@
 #include "gpu/command_buffer/service/gpu_switches.h"
 #include "gpu/ipc/service/switches.h"
 #include "ipc/ipc_channel_handle.h"
-#include "ipc/ipc_switches.h"
 #include "ipc/message_filter.h"
 #include "media/base/media_switches.h"
 #include "mojo/edk/embedder/embedder.h"
@@ -574,7 +573,7 @@ bool GpuProcessHost::Init() {
     DCHECK(g_gpu_main_thread_factory);
     in_process_gpu_thread_.reset(g_gpu_main_thread_factory(
         InProcessChildThreadParams(
-            std::string(), base::ThreadTaskRunnerHandle::Get(),
+            base::ThreadTaskRunnerHandle::Get(),
             process_->child_connection()->service_token()),
         gpu_preferences));
     base::Thread::Options options;