[Offline pages] Ensuring obtaining GcmNetworkManager in BackgroundScheduler does not throw

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

Index: chrome/android/junit/src/org/chromium/chrome/browser/offlinepages/ShadowGoogleApiAvailability.java
diff --git a/chrome/android/junit/src/org/chromium/chrome/browser/offlinepages/ShadowGoogleApiAvailability.java b/chrome/android/junit/src/org/chromium/chrome/browser/offlinepages/ShadowGoogleApiAvailability.java
new file mode 100644
index 0000000000000000000000000000000000000000..bb8bbb1298fb3791d220419393a2b3ccb7e2ac5e
--- /dev/null
+++ b/chrome/android/junit/src/org/chromium/chrome/browser/offlinepages/ShadowGoogleApiAvailability.java
@@ -0,0 +1,22 @@
+// Copyright 2017 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 android.content.Context;
+
+import com.google.android.gms.common.ConnectionResult;
+import com.google.android.gms.common.GoogleApiAvailability;
+
+import org.robolectric.annotation.Implementation;
+import org.robolectric.annotation.Implements;
+
+/** Custom shadow for the OS's GoogleApiAvailability. */
+@Implements(GoogleApiAvailability.class)
+public class ShadowGoogleApiAvailability {
+    @Implementation
+    public int isGooglePlayServicesAvailable(Context context) {
+        return ConnectionResult.SUCCESS;
+    }
+}