Add an Android sample app for Telemetry tests.

tools/android/android_tools.gyp

 # Copyright (c) 2012 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.
 
 {
   'targets': [
     # Intermediate target grouping the android tools needed to run native
     # unittests and instrumentation test apks.
     {
       # GN: //tools/android:android_tools
@@ skipping 67 matching lines @@
       ],
     },
     {
       # GN: //tools/android:audio_focus_grabber
       'target_name': 'audio_focus_grabber',
       'type': 'none',
       'dependencies': [
         'audio_focus_grabber/audio_focus_grabber.gyp:audio_focus_grabber_apk',
       ],
     },
+    {
+      # GN: //tools/android:push_apps_to_background
+      'target_name': 'push_apps_to_background',
+      'type': 'none',
+      'dependencies': [
+        'push_apps_to_background/push_apps_to_background.gyp:push_apps_to_background_apk',
+      ],
+    },
   ],
 }