mandoline sandbox: prewarm libraries before we raise the sandbox.

mojo/runner/child_process.mojom

Index: mojo/runner/child_process.mojom
diff --git a/mojo/runner/child_process.mojom b/mojo/runner/child_process.mojom
index da461c9c3e34d708260a6249865e04703fc957b0..ece1e6783115865e2fd3f1329cca1a7f0648fb6a 100644
--- a/mojo/runner/child_process.mojom
+++ b/mojo/runner/child_process.mojom
@@ -7,10 +7,8 @@ module mojo.runner;
 import "mojo/application/public/interfaces/application.mojom";
 
 interface ChildController {
-  // Starts the app at the given path (deleting it if |clean_app_path| is true).
-  StartApp(string app_path,
-           bool clean_app_path,
-           mojo.Application& application_request) => (int32 result);
+  // Starts the app.
+  StartApp(mojo.Application& application_request) => (int32 result);
 
   // Exits the child process now (with no cleanup), with the given exit code.
   ExitNow(int32 exit_code);