[Cronet] Move NetworkChangeNotifier initialization off UI thread

components/cronet/android/java/src/org/chromium/net/impl/NetworkChangeNotifierIniter.java

Index: components/cronet/android/java/src/org/chromium/net/impl/NetworkChangeNotifierIniter.java
diff --git a/components/cronet/android/java/src/org/chromium/net/impl/NetworkChangeNotifierIniter.java b/components/cronet/android/java/src/org/chromium/net/impl/NetworkChangeNotifierIniter.java
new file mode 100644
index 0000000000000000000000000000000000000000..8288a01f4f510e070226cfce6ff399ea0834c028
--- /dev/null
+++ b/components/cronet/android/java/src/org/chromium/net/impl/NetworkChangeNotifierIniter.java
@@ -0,0 +1,51 @@
+// 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.net.impl;
+
+import org.chromium.base.ContextUtils;
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+import org.chromium.net.NetworkChangeNotifier;
+
+import javax.annotation.concurrent.GuardedBy;
+
+/**
+ * Controls initialization of NetworkChangeNotifier.
+ */
+@JNINamespace("cronet")
+public class NetworkChangeNotifierIniter {
+    // Synchronize initialization.
+    private static final Object sInitLock = new Object();
+    // Has initialization completed?
+    @GuardedBy("sInitLock")
+    private static volatile boolean sInitDone = false;
+
+    /**
+     * Ensure that the NetworkChangeNotifier is initialized. Can be called from
+     * any thread, the initialization is performed on the first calling thread.
+     */
+    @CalledByNative
+    public static void init() {
+        synchronized (sInitLock) {
+            if (!sInitDone) {
+                NetworkChangeNotifier.init(ContextUtils.getApplicationContext());
+                // Registers to always receive network notifications. Note
+                // that this call is fine for Cronet because Cronet
+                // embedders do not have API access to create network change
+                // observers. Existing observers in the net stack do not
+                // perform expensive work.
+                NetworkChangeNotifier.registerToReceiveNotificationsAlways();
+                // registerToReceiveNotificationsAlways() is called before the native
+                // NetworkChangeNotifierAndroid is created, so as to avoid receiving
+                // the undesired initial network change observer notification, which
+                // will cause active requests to fail with ERR_NETWORK_CHANGED.
+                nativeNetworkChangeNotifierInit();
+                sInitDone = true;
+            }
+        }
+    }
+
+    private static native void nativeNetworkChangeNotifierInit();
+}