[Android WebView] Implement support for Network Information API and enable it.

android_webview/java/src/org/chromium/android_webview/AwNetworkChangeNotifierRegistrationPolicy.java

Index: android_webview/java/src/org/chromium/android_webview/AwNetworkChangeNotifierRegistrationPolicy.java
diff --git a/android_webview/java/src/org/chromium/android_webview/AwNetworkChangeNotifierRegistrationPolicy.java b/android_webview/java/src/org/chromium/android_webview/AwNetworkChangeNotifierRegistrationPolicy.java
new file mode 100644
index 0000000000000000000000000000000000000000..798a9af2d784031c62069545beeb696238f80bc7
--- /dev/null
+++ b/android_webview/java/src/org/chromium/android_webview/AwNetworkChangeNotifierRegistrationPolicy.java
@@ -0,0 +1,37 @@
+// Copyright 2016 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.android_webview;
+
+import org.chromium.net.NetworkChangeNotifierAutoDetect;
+
+/**
+ * Registration policy to make sure we only listen to network changes when
+ * there are live webview instances.
+ */
+public class AwNetworkChangeNotifierRegistrationPolicy
+        extends NetworkChangeNotifierAutoDetect.RegistrationPolicy
+        implements AwContentsLifecycleNotifier.Observer {
+
+    @Override
+    protected void init(NetworkChangeNotifierAutoDetect notifier) {
+        super.init(notifier);
+        AwContentsLifecycleNotifier.addObserver(this);
+    }
+
+    protected void destroy() {
+        AwContentsLifecycleNotifier.removeObserver(this);
+    }
+
+    // AwContentsLifecycleNotifier.Observer
+    @Override
+    public void onFirstWebViewCreated() {
+        register();
+    }
+
+    @Override
+    public void onLastWebViewDestroyed() {
+        unregister();
+    }
+}