Add base/android/activity_status.cc

base/android/activity_status.cc

Index: base/android/activity_status.cc
diff --git a/base/android/activity_status.cc b/base/android/activity_status.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4d0be32ef93202a34b636916cf1e9fda640cdd8b
--- /dev/null
+++ b/base/android/activity_status.cc
@@ -0,0 +1,66 @@
+// 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.
+
+#include "base/android/activity_status.h"
+
+#include <jni.h>
+
+#include "base/memory/singleton.h"
+#include "jni/ActivityStatus_jni.h"
+
+namespace base {
+namespace android {
+
+ActivityStatus::Listener::Listener(
+    const ActivityStatus::StateChangeCallback& callback)
+    : callback_(callback) {
+  ActivityStatus::GetInstance()->RegisterListener(this);
+}
+
+ActivityStatus::Listener::~Listener() {
+  ActivityStatus::GetInstance()->UnregisterListener(this);
+}
+
+void ActivityStatus::Listener::Notify(ActivityState state) {
+  callback_.Run(state);
+}
+
+// static
+ActivityStatus* ActivityStatus::GetInstance() {
+  return Singleton<ActivityStatus,
+                   LeakySingletonTraits<ActivityStatus> >::get();
+}
+
+static void OnActivityStateChange(JNIEnv* env, jclass clazz, int new_state) {
+  ActivityStatus* activity_status = ActivityStatus::GetInstance();
+  ActivityState activity_state = static_cast<ActivityState>(new_state);
+  activity_status->OnActivityStateChange(activity_state);
+}
+
+bool ActivityStatus::RegisterBindings(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+ActivityStatus::ActivityStatus()
+    : observers_(new ObserverListThreadSafe<Listener>()) {
+  Java_ActivityStatus_registerThreadSafeNativeStateListener(
+      base::android::AttachCurrentThread());
+}
+
+ActivityStatus::~ActivityStatus() {}
+
+void ActivityStatus::RegisterListener(Listener* listener) {
+  observers_->AddObserver(listener);
+}
+
+void ActivityStatus::UnregisterListener(Listener* listener) {
+  observers_->RemoveObserver(listener);
+}
+
+void ActivityStatus::OnActivityStateChange(ActivityState new_state) {
+  observers_->Notify(&ActivityStatus::Listener::Notify, new_state);
+}
+
+}  // namespace android
+}  // namespace base