mustash: enable GPU Compositing in renderer

content/browser/renderer_host/render_process_host_impl.cc

Index: content/browser/renderer_host/render_process_host_impl.cc
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index 04a1a13951833933eb8a0a879fce09f4cc246c86..4de35ff76585c3da1d53afe48bd54ec4121a3b90 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -123,6 +123,7 @@
 #include "content/common/in_process_child_thread_params.h"
 #include "content/common/mojo/channel_init.h"
 #include "content/common/mojo/mojo_messages.h"
+#include "content/common/mojo/mojo_shell_connection_impl.h"
 #include "content/common/render_process_messages.h"
 #include "content/common/resource_messages.h"
 #include "content/common/site_isolation_policy.h"
@@ -1543,6 +1544,11 @@ void RenderProcessHostImpl::PropagateBrowserCommandLineToRenderer(
       renderer_cmd->AppendSwitch(switches::kWaitForDebugger);
     }
   }
+
+#if defined(MOJO_SHELL_CLIENT)
+  if (IsRunningInMojoShell())
+    renderer_cmd->AppendSwitch(switches::kEnableMojoShellConnection);
+#endif
 }
 
 base::ProcessHandle RenderProcessHostImpl::GetHandle() const {