android: Pass CPU properties from browser to renderer process.

base/android/java/src/org/chromium/base/CpuFeatures.java

+// 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.
+
+package org.chromium.base;
+
+// The only purpose of this class is to allow sending CPU properties
+// from the browser process to sandboxed renderer processes. This is
+// needed because sandboxed processes cannot, on ARM, query the kernel
+// about the CPU's properties by parsing /proc, so this operation must
+// be performed in the browser process, and the result passed to
+// renderer ones.
+//
+// For more context, see http://crbug.com/164154
+//
+// Technically, this is a wrapper around the native NDK cpufeatures
+// library. The exact CPU features bits are never used in Java so
+// there is no point in duplicating their definitions here.
+//
+@JNINamespace("base::android")
+public abstract class CpuFeatures {
+    /**
+     * Return the number of CPU Cores on the device.
+     */
+    public static int getCount() {
+        return nativeGetCoreCount();
+    }
+
+    /**
+     * Return the CPU feature mask.
+     * This is a 64-bit integer that corresponds to the CPU's features.
+     * The value comes directly from android_getCpuFeatures().
+     */
+     public static long getMask() {
+        return nativeGetCpuFeatures();
+     }
+
+    private static native int nativeGetCoreCount();
+    private static native long nativeGetCpuFeatures();
+}