Update from https://crrev.com/320343

sandbox/linux/bpf_dsl/trap_registry.h

Index: sandbox/linux/bpf_dsl/trap_registry.h
diff --git a/sandbox/linux/bpf_dsl/trap_registry.h b/sandbox/linux/bpf_dsl/trap_registry.h
index 94d4722c8cc359dce0574f0982279b0d1e5d58db..0a5d2f14cccfcd2c51ed80e7bfa39d8811d79464 100644
--- a/sandbox/linux/bpf_dsl/trap_registry.h
+++ b/sandbox/linux/bpf_dsl/trap_registry.h
@@ -49,10 +49,19 @@ class SANDBOX_EXPORT TrapRegistry {
 
   // EnableUnsafeTraps tries to enable unsafe traps and returns
   // whether it was successful. This is a one-way operation.
+  //
+  // CAUTION: Enabling unsafe traps effectively defeats the security
+  // guarantees provided by the sandbox policy. TrapRegistry
+  // implementations should ensure unsafe traps are only enabled
+  // during testing.
   virtual bool EnableUnsafeTraps() = 0;
 
  protected:
   TrapRegistry() {}
+
+  // TrapRegistry's destructor is intentionally non-virtual so that
+  // implementations can omit their destructor.  Instead we protect against
+  // misuse by marking it protected.
   ~TrapRegistry() {}
 
   DISALLOW_COPY_AND_ASSIGN(TrapRegistry);