Add namespace sandbox status to LinuxSandbox::GetStatus.

content/public/common/sandbox_linux.h

Index: content/public/common/sandbox_linux.h
diff --git a/content/public/common/sandbox_linux.h b/content/public/common/sandbox_linux.h
index c29c9f107cbc6ef6310fb96c3ff332694fbd2399..acee4037e74a9a31cdb9c3f17f90a08f295c790f 100644
--- a/content/public/common/sandbox_linux.h
+++ b/content/public/common/sandbox_linux.h
@@ -14,10 +14,10 @@ enum LinuxSandboxStatus {
   // SUID sandbox active.
   kSandboxLinuxSUID = 1 << 0,
 
-  // SUID sandbox is using the PID namespace.
+  // Sandbox is using a new PID namespace.
   kSandboxLinuxPIDNS = 1 << 1,
 
-  // SUID sandbox is using the network namespace.
+  // Sandbox is using a new network namespace.
   kSandboxLinuxNetNS = 1 << 2,
 
   // seccomp-bpf sandbox active.
@@ -29,6 +29,9 @@ enum LinuxSandboxStatus {
   // seccomp-bpf sandbox is active and the kernel supports TSYNC.
   kSandboxLinuxSeccompTSYNC = 1 << 5,
 
+  // User namespace sandbox active.
+  kSandboxLinuxUserNS = 1 << 6,
+
   // A flag that denotes an invalid sandbox status.
   kSandboxLinuxInvalid = 1 << 31,
 };