Add a mechanism to launch the utility process from the zygote on Linux.

content/browser/utility_process_host.h

Index: content/browser/utility_process_host.h
diff --git a/content/browser/utility_process_host.h b/content/browser/utility_process_host.h
index b81d12d2016ae49c19c4aa063861b9e65c063b5e..1481d449a081afcb47cc25283f5bf75521a7b6f8 100644
--- a/content/browser/utility_process_host.h
+++ b/content/browser/utility_process_host.h
@@ -66,6 +66,7 @@ class CONTENT_EXPORT UtilityProcessHost : public BrowserChildProcessHost {
   void set_exposed_dir(const FilePath& dir) { exposed_dir_ = dir; }
   void set_no_sandbox(bool flag) { no_sandbox_ = flag; }
   void set_child_flags(int flags) { child_flags_ = flags; }
+  void set_use_linux_zygote(bool flag) { use_linux_zygote_ = flag; }
 #if defined(OS_POSIX)
   void set_env(const base::environment_vector& env) { env_ = env; }
 #endif
@@ -102,6 +103,11 @@ class CONTENT_EXPORT UtilityProcessHost : public BrowserChildProcessHost {
   // Flags defined in ChildProcessHost with which to start the process.
   int child_flags_;
 
+  // If the |no_sandbox_| flag is off, and we are on Linux, launch the
+  // utility process from the zygote. Defaults to false.
+  // Can only be used for tasks that do not require FS access.
+  bool use_linux_zygote_;
+
   base::environment_vector env_;
 
   bool started_;