Add unit tests for the Background Scheduler.

chrome/android/junit/src/org/chromium/chrome/browser/offlinepages/ShadowGcmNetworkManager.java

Index: chrome/android/junit/src/org/chromium/chrome/browser/offlinepages/ShadowGcmNetworkManager.java
diff --git a/chrome/android/junit/src/org/chromium/chrome/browser/offlinepages/ShadowGcmNetworkManager.java b/chrome/android/junit/src/org/chromium/chrome/browser/offlinepages/ShadowGcmNetworkManager.java
new file mode 100644
index 0000000000000000000000000000000000000000..8a2189e334336dd4e88b0ad0bf7a7a8fc032e901
--- /dev/null
+++ b/chrome/android/junit/src/org/chromium/chrome/browser/offlinepages/ShadowGcmNetworkManager.java
@@ -0,0 +1,31 @@
+// 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.chrome.browser.offlinepages;
+
+import com.google.android.gms.gcm.GcmNetworkManager;
+import com.google.android.gms.gcm.Task;
+
+import org.robolectric.annotation.Implementation;
+import org.robolectric.annotation.Implements;
+
+
+/**
+ * Custom shadow for the OS's GcmNetworkManager.  We use this to hook the call to GcmNetworkManager
+ * to make sure it was invoked as we expect.
+ */
+@Implements(GcmNetworkManager.class)
+public class ShadowGcmNetworkManager {
+    private static Task sTask;
+
+    @Implementation
+    public void schedule(Task task) {
+        // Capture the string part divisions so we can check them.
+        sTask = task;
+    }
+
+    public static Task getScheduledTask() {
+        return sTask;
+    }
+}