Receive app notifications in SimpleCache, so we save our index file

net/android/simple_cache_activity_status_notifier.h

+// 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.
+
+#ifndef NET_ANDROID_SIMPLE_CACHE_ACTIVITY_STATUS_NOTIFIER_H_
+#define NET_ANDROID_SIMPLE_CACHE_ACTIVITY_STATUS_NOTIFIER_H_
+
+#include <jni.h>
+
+#include "base/android/jni_android.h"
+#include "base/basictypes.h"
+#include "base/callback.h"
+#include "base/memory/ref_counted.h"
+#include "base/threading/thread_checker.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+
+namespace net {
+
+// This class is the native twin of the class with same name in
+// SimpleCacheActivityStatusNotifier.java
+// This is used by the SimpleIndex in net/disk_cache/simple/ to listens to
+// changes in the android app state such as the app going to the background or
+// foreground.
+class SimpleCacheActivityStatusNotifier {
+public:
+  // This enum must match the constants defined in
+  // ./base/android/java/src/org/chromium/base/ActivityStatus.java
+  enum ActivityStatus {
+    CREATED = 1,
+    STARTED = 2,
+    RESUMED = 3,
+    PAUSED = 4,
+    STOPPED = 5,
+    DESTROYED = 6
+  };
+
+  typedef base::Callback<void(ActivityStatus activity_status)>
+      ActivityStatusChangedCallback;
+
+  SimpleCacheActivityStatusNotifier(
+      const ActivityStatusChangedCallback& notify_callback);
+
+  ~SimpleCacheActivityStatusNotifier();
+
+  void NotifyActivityStatusChanged(JNIEnv* env,
+                                   jobject obj,
+                                   jint new_activity_status);
+
+  static bool Register(JNIEnv* env);
+
+private:
+  base::android::ScopedJavaGlobalRef<jobject> java_obj_;
+  const ActivityStatusChangedCallback notify_callback_;
+  base::ThreadChecker thread_checker_;
+};
+
+}  // namespace net
+
+#endif  // NET_ANDROID_SIMPLE_CACHE_ACTIVITY_STATUS_NOTIFIER_H_