Cache JNI call results in SysUtils on native side.

base/android/sys_utils.h

 // Copyright 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.
 
 #ifndef BASE_ANDROID_SYS_UTILS_H_
 #define BASE_ANDROID_SYS_UTILS_H_
 
 #include "base/android/jni_android.h"
 
 namespace base {
 namespace android {
 
 class BASE_EXPORT SysUtils {
  public:
   static bool Register(JNIEnv* env);
 
   // Returns true iff this is a low-end device.
   static bool IsLowEndDevice();
 
   // Return the device's RAM size in kilo-bytes. Used for testing.
   static size_t AmountOfPhysicalMemoryKB();
 
  private:
   SysUtils();
+
+  static bool IsLowEndDeviceFromJni();
+  static size_t AmountOfPhysicalMemoryKBFromJni();
 };
 
 }  // namespace android
 }  // namespace base
 
 #endif  // BASE_ANDROID_SYS_UTILS_H_