[Android WebView] Enable Network Information API

Enable Network Information API for Webview by default.

The API is *not* enabled in the following cases:
1. if the embedding application does not have sufficient permissions
(i.e. at least android.permission.ACCESS_NETWORK_STATE) and
2. when there are no WebView instances (i.e. instances of AwContents).

BUG=520088

Review URL: https://codereview.chromium.org/1297943003

Cr-Commit-Position: refs/heads/master@{#344569}

1 files changed, 61 insertions, 0 deletions

diff --git a/android_webview/java/src/org/chromium/android_webview/AwWebViewLifecycleObserver.java b/android_webview/java/src/org/chromium/android_webview/AwWebViewLifecycleObserver.java
new file mode 100644
index 0000000..a9b52ca
--- /dev/null
+++ b/android_webview/java/src/org/chromium/android_webview/AwWebViewLifecycleObserver.java
@@ -0,0 +1,61 @@
+// 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.
+
+package org.chromium.android_webview;
+
+import android.content.Context;
+
+import org.chromium.base.ThreadUtils;
+import org.chromium.base.VisibleForTesting;
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+import org.chromium.net.NetworkChangeNotifier;
+
+/**
+ * This class is intended to observe the lifetime of webviews. It receives
+ * a callback when the first webview instance (native aw_content) is created
+ * and when the last webview instance is destroyed.
+ */
+@JNINamespace("android_webview")
+public class AwWebViewLifecycleObserver {
+
+    private static final String TAG = "AwWebViewLifecycle";
+    // Assume there is ACCESS_NETWORK_STATE permission unless told otherwise.
+    private static boolean sHasNetworkStatePermission = true;
+
+    // Called on UI thread.
+    @CalledByNative
+    private static void onFirstWebViewCreated(Context appContext) {
+        ThreadUtils.assertOnUiThread();
+
+        if (sHasNetworkStatePermission) {
+            try {
+                if (!NetworkChangeNotifier.isInitialized()) {
+                    NetworkChangeNotifier.init(appContext);
+                }
+                NetworkChangeNotifier.registerToReceiveNotificationsAlways();
+            } catch (SecurityException e) {
+                // Cannot enable network information api. The application does not have the
+                // ACCESS_NETWORK_STATE permission.
+                sHasNetworkStatePermission = false;
+            }
+        }
+    }
+
+    // Called on UI thread.
+    @CalledByNative
+    private static void onLastWebViewDestroyed(Context appContext) {
+        ThreadUtils.assertOnUiThread();
+
+        if (sHasNetworkStatePermission && NetworkChangeNotifier.isInitialized()) {
+            // Force unregister for network change broadcasts.
+            NetworkChangeNotifier.setAutoDetectConnectivityState(false);
+        }
+    }
+
+    @VisibleForTesting
+    public static void setHasNetworkStatePermission(boolean allow) {
+        sHasNetworkStatePermission = allow;
+    }
+}