Fix "unused variable" warnings.

content/common/sandbox_linux/bpf_cros_arm_gpu_policy_linux.cc

 // Copyright (c) 2013 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 "content/common/sandbox_linux/bpf_cros_arm_gpu_policy_linux.h"
 
 #include <dlfcn.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/socket.h>
@@ skipping 100 matching lines @@
     case __NR_openat:
       return Allow();
     default:
       return CrosArmGpuProcessPolicy::EvaluateSyscall(sysno);
   }
 }
 
 }  // namespace
 
 CrosArmGpuProcessPolicy::CrosArmGpuProcessPolicy(bool allow_shmat)
-    : allow_shmat_(allow_shmat) {}
+#if defined(__arm__) || defined(__aarch64__)
+    : allow_shmat_(allow_shmat)
+#endif
+{
+}
 
 CrosArmGpuProcessPolicy::~CrosArmGpuProcessPolicy() {}
 
 ResultExpr CrosArmGpuProcessPolicy::EvaluateSyscall(int sysno) const {
 #if defined(__arm__) || defined(__aarch64__)
   if (allow_shmat_ && sysno == __NR_shmat)
     return Allow();
 #endif  // defined(__arm__) || defined(__aarch64__)
 
   switch (sysno) {
@@ skipping 37 matching lines @@
   // Preload the Tegra V4L2 (video decode acceleration) library.
   dlopen("/usr/lib/libtegrav4l2.so", dlopen_flag);
   // Resetting errno since platform-specific libraries will fail on other
   // platforms.
   errno = 0;
 
   return true;
 }
 
 }  // namespace content