Add SeccompSupportDetector for Android.

chrome/browser/android/seccomp_support_detector.h

+// Copyright 2015 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 CHROME_BROWSER_ANDROID_SECCOMP_SUPPORT_DETECTOR_H_
+#define CHROME_BROWSER_ANDROID_SECCOMP_SUPPORT_DETECTOR_H_
+
+#include "base/compiler_specific.h"
+#include "content/public/browser/utility_process_host_client.h"
+
+// This class is used to report via UMA the Android kernel version and
+// level of seccomp-bpf support. The kernel version is read from the FILE
+// thread, while seccomp support is tested in a utility process, in case
+// the probing causes a crash.
+class SeccompSupportDetector : public content::UtilityProcessHostClient {
+ public:
+  // Starts the detection process. This should be called once per browser
+  // session. This is safe to call from any thread.
+  static void StartDetection();
+
+ private:
+  SeccompSupportDetector();
+  ~SeccompSupportDetector() override;
+
+  // Called on the FILE thread. This reads the utsname and records the kernel

[Lei Zhang, 2015/03/19 18:32:04]

s/FILE thread/blocking thread pool/

[Robert Sesek, 2015/03/19 19:37:16]

Done.

+  // version.
+  void DetectKernelVersion();
+
+  // Called on the IO thread. This starts a utility process to detect seccomp.
+  void DetectSeccomp();
+
+  // UtilityProcessHostClient:
+  void OnProcessCrashed(int exit_code) override;
+  bool OnMessageReceived(const IPC::Message& message) override;
+
+  // OnDetectPrctl is always received before OnDetectSyscall.
+  void OnDetectPrctl(bool prctl_supported);
+  void OnDetectSyscall(bool syscall_supported);
+
+  // Whether OnDetectPrctl was received.
+  bool prctl_detected_;
+
+  DISALLOW_COPY_AND_ASSIGN(SeccompSupportDetector);
+};
+
+#endif  // CHROME_BROWSER_ANDROID_SECCOMP_SUPPORT_DETECTOR_H_