Create a LinuxSandbox class.

sandbox/linux/suid/client/setuid_sandbox_client.cc

Index: sandbox/linux/suid/client/setuid_sandbox_client.cc
diff --git a/sandbox/linux/suid/client/setuid_sandbox_client.cc b/sandbox/linux/suid/client/setuid_sandbox_client.cc
index 749d2d099e3dcd820529c558fea6eb1f877a3a02..4f62d097cbcdd389a1a7b87413f790aaeffdbd21 100644
--- a/sandbox/linux/suid/client/setuid_sandbox_client.cc
+++ b/sandbox/linux/suid/client/setuid_sandbox_client.cc
@@ -103,8 +103,9 @@ SetuidSandboxClient* SetuidSandboxClient::Create() {
   return sandbox_client;
 }
 
-SetuidSandboxClient::SetuidSandboxClient() {
-  env_ = NULL;
+SetuidSandboxClient::SetuidSandboxClient()
+    : env_(NULL),
+      sandboxed_(false) {
 }
 
 SetuidSandboxClient::~SetuidSandboxClient() {
@@ -142,6 +143,10 @@ bool SetuidSandboxClient::ChrootMe() {
     LOG(ERROR) << "Error code reply from chroot helper";
     return false;
   }
+
+  // We now consider ourselves "fully sandboxed" as far as the
+  // setuid sandbox is concerned.
+  sandboxed_ = true;
   return true;
 }
 
@@ -161,6 +166,10 @@ bool SetuidSandboxClient::IsInNewNETNamespace() const {
   return env_->HasVar(kSandboxNETNSEnvironmentVarName);
 }
 
+bool SetuidSandboxClient::IsSandboxed() const {
+  return sandboxed_;
+}
+
 void SetuidSandboxClient::SetupLaunchEnvironment() {
   SaveSUIDUnsafeEnvironmentVariables(env_);
   SetSandboxAPIEnvironmentVariable(env_);