Reland of [Background Sync] Trigger Background Sync events when Chrome is backgrounded on Android

content/browser/android/background_sync_network_observer_android.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 CONTENT_BROWSER_ANDROID_BACKGROUND_SYNC_NETWORK_OBSERVER_ANDROID_H_
+#define CONTENT_BROWSER_ANDROID_BACKGROUND_SYNC_NETWORK_OBSERVER_ANDROID_H_
+
+#include "base/android/jni_android.h"
+#include "base/android/scoped_java_ref.h"
+#include "base/memory/weak_ptr.h"
+#include "content/browser/background_sync/background_sync_network_observer.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace content {
+
+// BackgroundSyncNetworkObserverAndroid is a specialized
+// BackgroundSyncNetworkObserver which is backed by a NetworkChangeNotifier
+// that listens for network events even when the browser is paused, unlike the
+// standard NetworkChangeNotifier. This ensures that sync events can be fired
+// even when the browser is backgrounded, and other network observers are
+// disabled.
+class BackgroundSyncNetworkObserverAndroid
+    : public BackgroundSyncNetworkObserver {
+ public:
+  // Creates a BackgroundSyncNetworkObserver. |network_changed_callback| is
+  // called via PostMessage when the network connection changes.
+  BackgroundSyncNetworkObserverAndroid(
+      const base::Closure& network_changed_callback);
+
+  ~BackgroundSyncNetworkObserverAndroid() override;
+
+  // This class lives on the UI thread and mediates all access to the Java
+  // BackgroundSyncNetworkObserver, which it creates and owns. It is in turn
+  // owned by the BackgroundSyncNetworkObserverAndroid.
+  class Observer : public base::RefCountedThreadSafe<
+                       BackgroundSyncNetworkObserverAndroid::Observer,
+                       content::BrowserThread::DeleteOnUIThread> {
+   public:
+    static scoped_refptr<BackgroundSyncNetworkObserverAndroid::Observer> Create(
+        base::Callback<void(net::NetworkChangeNotifier::ConnectionType)>
+            callback);
+
+    static bool RegisterNetworkObserver(JNIEnv* env);
+
+    // Called from BackgroundSyncNetworkObserver.java over JNI whenever the
+    // connection type changes. This updates the current connection type seen by
+    // this class and calls the |network_changed_callback| provided to the
+    // constructor, on the IO thread, with the new connection type.
+    void NotifyConnectionTypeChanged(JNIEnv* env,
+                                     jobject jcaller,
+                                     jint new_connection_type);
+
+   private:
+    friend struct BrowserThread::DeleteOnThread<BrowserThread::UI>;
+    friend class base::DeleteHelper<
+        BackgroundSyncNetworkObserverAndroid::Observer>;
+
+    Observer(base::Callback<void(net::NetworkChangeNotifier::ConnectionType)>
+                 callback);
+    void Init();
+    ~Observer();
+
+    // This callback is to be run on the IO thread whenever the connection type
+    // changes.
+    base::Callback<void(net::NetworkChangeNotifier::ConnectionType)> callback_;
+    base::android::ScopedJavaGlobalRef<jobject> j_observer_;
+
+    DISALLOW_COPY_AND_ASSIGN(Observer);
+  };
+
+ private:
+  // Accessed on UI Thread
+  scoped_refptr<Observer> observer_;
+
+  base::WeakPtrFactory<BackgroundSyncNetworkObserverAndroid> weak_ptr_factory_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_ANDROID_BACKGROUND_SYNC_NETWORK_OBSERVER_ANDROID_H_