Add test runner scripts for instrumentation tests

BUG=599919
NOTRY=True
TBR=perkj@webrtc.org

Review URL: https://codereview.webrtc.org/1863363002

Cr-Commit-Position: refs/heads/master@{#12294}
diff --git a/webrtc/webrtc_examples.gyp b/webrtc/webrtc_examples.gyp
index d5d8ade..4a1ff0a 100755
--- a/webrtc/webrtc_examples.gyp
+++ b/webrtc/webrtc_examples.gyp
@@ -454,8 +454,13 @@
             'apk_name': 'AppRTCDemoTest',
             'java_in_dir': 'examples/androidtests',
             'is_test_apk': 1,
+            'test_type': 'instrumentation',
+            'test_runner_path': '<(DEPTH)/webrtc/build/android/test_runner.py',
           },
-          'includes': [ '../build/java_apk.gypi' ],
+          'includes': [
+            '../build/java_apk.gypi',
+            '../build/android/test_runner.gypi',
+          ],
         },
       ],  # targets
     }],  # OS=="android"