mandoline sandbox: prewarm libraries before we raise the sandbox.

mojo/runner/child_process_host.cc

Index: mojo/runner/child_process_host.cc
diff --git a/mojo/runner/child_process_host.cc b/mojo/runner/child_process_host.cc
index d5d2104d8225ca59cea7d84514ac35b36413feb4..1cf288c4ebcdade9db0c95794295ba526a744fe2 100644
--- a/mojo/runner/child_process_host.cc
+++ b/mojo/runner/child_process_host.cc
@@ -82,7 +82,7 @@ void ChildProcessHost::StartApp(
 
   on_app_complete_ = on_app_complete;
   controller_->StartApp(
-      app_path_.AsUTF8Unsafe(), clean_app_path_, application_request.Pass(),
+      application_request.Pass(),
       base::Bind(&ChildProcessHost::AppCompleted, base::Unretained(this)));
 }
 
@@ -109,6 +109,9 @@ bool ChildProcessHost::DoLaunch() {
   child_command_line.AppendArguments(*parent_command_line, false);
   child_command_line.AppendSwitchPath(switches::kChildProcess, app_path_);
 
+  if (clean_app_path_)
+    child_command_line.AppendSwitch(switches::kDeleteAfterLoad);
+
   if (start_sandboxed_)
     child_command_line.AppendSwitch(switches::kEnableSandbox);