Enable one PID namespace per process for NaCl processes.

sandbox/linux/services/namespace_sandbox.h

Index: sandbox/linux/services/namespace_sandbox.h
diff --git a/sandbox/linux/services/namespace_sandbox.h b/sandbox/linux/services/namespace_sandbox.h
index 80097fb16afa625415070e8e581540e514e67abf..474ca6cb554621b820988c0aea4ca71f66118bd8 100644
--- a/sandbox/linux/services/namespace_sandbox.h
+++ b/sandbox/linux/services/namespace_sandbox.h
@@ -18,6 +18,10 @@
 
 namespace sandbox {
 
+inline int SignalExitCode(int sig) {

[jln (very slow on Chromium), 2015/05/28 09:02:33]

Let's qualify this in NamespaceSandbox:: as a static member.

sandbox::something should pretty much not exist.

[rickyz (no longer on Chrome), 2015/05/29 23:16:39]

Done.

+  return -sig & 0xff;
+}
+
 // Helper class for starting a process inside a new user, PID, and network
 // namespace. Before using a namespace sandbox, check for namespaces support
 // using Credentials::CanCreateProcessInNewUserNS.
@@ -38,8 +42,6 @@ namespace sandbox {
 class SANDBOX_EXPORT NamespaceSandbox {
  public:
 #if !defined(OS_NACL_NONSFI)
-  static const int kDefaultExitCode = 1;
-
   // Launch a new process inside its own user/PID/network namespaces (depending
   // on kernel support). Requires at a minimum that user namespaces are
   // supported (use Credentials::CanCreateProcessInNewUserNS to check this).
@@ -70,8 +72,8 @@ class SANDBOX_EXPORT NamespaceSandbox {
   //
   // SIGHUP, SIGINT, SIGABRT, SIGQUIT, SIGPIPE, SIGTERM, SIGUSR1, SIGUSR2
   //
-  // that exits with kDefaultExitCode. These are signals whose default action is
-  // to terminate the program (apart from SIGILL, SIGFPE, and SIGSEGV, which
+  // that exits with SignalExitCode(sig). These are signals whose default action
+  // is to terminate the program (apart from SIGILL, SIGFPE, and SIGSEGV, which
   // will still terminate the process if e.g. an illegal instruction is
   // encountered, etc.).
   //