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

Allow the users of the utility process to specify whether the zygote
should be used on Linux. This will allow sandboxing the uses of the
utility process that don't do FS access.

This is the first step to get the utility process sandboxed
on Linux. Since most of the uses of the utility process
don't do file access, launching all of those from the zygote
will simplify sandboxing the one that does: extension
unpacking.

Subsequent CLs will port the uses of the utility process
that don't do file access to launch from the zygote.

BUG=93109
TEST=No functional changes yet, but test that nothing broke by
running browser_tests::ExtensionWebstorePrivateApiTest.* and also
logging into Chromium and installing an extension from the Web Store.


Review URL: http://codereview.chromium.org/8849007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@113914 0039d316-1c4b-4281-b951-d872f2087c98

content/app/content_main.cc

@@ -192,6 +192,7 @@ int RunZygote(const content::MainFunctionParams& main_function_params,
     { switches::kRendererProcess,    RendererMain },
     { switches::kWorkerProcess,      WorkerMain },
     { switches::kPpapiPluginProcess, PpapiPluginMain },
+    { switches::kUtilityProcess,     UtilityMain },
   };
 
   scoped_ptr<content::ZygoteForkDelegate> zygote_fork_delegate;

content/browser/utility_process_host.cc

@@ -46,6 +46,7 @@ UtilityProcessHost::UtilityProcessHost(Client* client,
 #else
       child_flags_(ChildProcessHost::CHILD_NORMAL),
 #endif
+      use_linux_zygote_(false),
       started_(false) {
 }
 
@@ -129,11 +130,17 @@ bool UtilityProcessHost::StartProcess() {
   cmd_line->AppendSwitchPath(switches::kUtilityProcessAllowedDir, exposed_dir_);
 #endif
 
+  bool use_zygote = false;
+
+#if defined(OS_LINUX)
+  use_zygote = !no_sandbox_ && use_linux_zygote_;
+#endif
+
   Launch(
 #if defined(OS_WIN)
       exposed_dir_,
 #elif defined(OS_POSIX)
-      false,
+      use_zygote,
       env_,
 #endif
       cmd_line);

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_;