Linux sandbox: cleanup sandbox-bpf naming.

sandbox/linux/seccomp-bpf/instruction.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SANDBOX_LINUX_SECCOMP_BPF_INSTRUCTION_H__
 #define SANDBOX_LINUX_SECCOMP_BPF_INSTRUCTION_H__
 
 #include <stdint.h>
 
-namespace playground2 {
+namespace sandbox {
 
 // The fields in this structure have the same meaning as the corresponding
 // fields in "struct sock_filter". See <linux/filter.h> for a lot more
 // detail.
 // code     -- Opcode of the instruction. This is typically a bitwise
 //             combination BPF_XXX values.
 // k        -- Operand; BPF instructions take zero or one operands. Operands
 //             are 32bit-wide constants, if present. They can be immediate
 //             values (if BPF_K is present in "code_"), addresses (if BPF_ABS
 //             is present in "code_"), or relative jump offsets (if BPF_JMP
@@ skipping 29 matching lines @@
     };
 
     // While assembling the BPF program, non-jumping instructions are linked
     // by the "next_" pointer. This field is no longer needed when we have
     // computed basic blocks.
     Instruction* next;
   };
   uint32_t k;
 };
 
-}  // namespace
+}  // namespace sandbox
 
 #endif  // SANDBOX_LINUX_SECCOMP_BPF_INSTRUCTION_H__