android: Improve ActivityStatus and add ChromiumActivity.

base/android/java/src/org/chromium/base/ChromiumActivity.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;
+
+import android.app.Activity;
+import android.os.Bundle;
+
+// All Chromium main activities should extend this class.
+// This allows various sub-systems to properly react to activity
+// state changes.
+public class ChromiumActivity extends Activity {
+
+  @Override
+  protected void onCreate(Bundle savedInstance) {
+    super.onCreate(savedInstance);
+    ActivityStatus.onStateChange(this, ActivityStatus.CREATED);
+  }
+
+  @Override
+  protected void onStart() {
+    super.onStart();
+    ActivityStatus.onStateChange(this, ActivityStatus.STARTED);
+  }
+
+  @Override
+  protected void onResume() {
+    super.onResume();
+    ActivityStatus.onStateChange(this, ActivityStatus.STARTED);
+  }
+
+  @Override
+  protected void onPause() {
+    ActivityStatus.onStateChange(this, ActivityStatus.STARTED);
+    super.onPause();
+  }
+
+  @Override
+  protected void onStop() {
+    ActivityStatus.onStateChange(this, ActivityStatus.STARTED);
+    super.onStop();
+  }
+
+  @Override
+  protected void onDestroy() {
+    ActivityStatus.onStateChange(this, ActivityStatus.DESTROYED);
+    super.onDestroy();
+  }
+}