Push API: test that default notification is shown on Android when needed.

chrome/android/java/src/org/chromium/chrome/browser/push_messaging/PushMessagingServiceObserver.java

Index: chrome/android/java/src/org/chromium/chrome/browser/push_messaging/PushMessagingServiceObserver.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/push_messaging/PushMessagingServiceObserver.java b/chrome/android/java/src/org/chromium/chrome/browser/push_messaging/PushMessagingServiceObserver.java
new file mode 100644
index 0000000000000000000000000000000000000000..2da8508e701c26d48a73f2093f7970cb0c1193fa
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/push_messaging/PushMessagingServiceObserver.java
@@ -0,0 +1,56 @@
+// 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.chrome.browser.push_messaging;
+
+import org.chromium.base.ThreadUtils;
+import org.chromium.base.VisibleForTesting;
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+
+import javax.annotation.Nullable;
+
+/**
+ * Observes events and changes in the PushMessagingService.
+ *
+ * Threading model: UI thread only.
+ *
+ * TODO(peter): Delete this class once delivery receipts are implemented and use those instead. This
+ *              really only exists for test purposes.
+ */
+@JNINamespace("chrome::android")
+public class PushMessagingServiceObserver {
+    /**
+     * The listener that needs to be notified of events and changes observed by the
+     * PushMessagingServiceObserver. May be null.
+     */
+    @Nullable private static Listener sListener;
+
+    /**
+     * Interface for the listener that needs to be notified of events and changes observed by the
+     * PushMessagingServiceObserver.
+     */
+    public interface Listener {
+        /**
+         * Called when a push message has been handled.
+         */
+        void onMessageHandled();
+    }
+
+    @VisibleForTesting
+    public static void setListenerForTesting(@Nullable Listener listener) {
+        ThreadUtils.assertOnUiThread();
+        sListener = listener;
+    }
+
+    @CalledByNative
+    private static void onMessageHandled() {
+        ThreadUtils.assertOnUiThread();
+        if (sListener != null) {
+            sListener.onMessageHandled();
+        }
+    }
+
+    private PushMessagingServiceObserver() {} // Private. Not meant to be instantiated.
+}