[MIPS] Support for MIPS PNaCl in PPAPI

ppapi/native_client/src/trusted/plugin/arch_mips/sandbox_isa.cc

 // 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.
 
 #include "ppapi/native_client/src/trusted/plugin/nexe_arch.h"
 
 namespace {
-// The list of supported ISA strings for ARM.  See issue:
+// The list of supported ISA strings for MIPS.  See issue:
 //   http://code.google.com/p/nativeclient/issues/detail?id=1040 for more
 // information.  Note that these string are to be case-insensitive compared.
-const char* const kNexeArchARM = "arm";
+const char* const kNexeArchMIPS = "mips32";
 }  // namespace
 
 namespace plugin {
 const char* GetSandboxISA() {
-  return kNexeArchARM;
+  return kNexeArchMIPS;
 }
 }  // namespace plugin