Add option to push files to device using isolate for instrumentation tests.

content/content_shell_test_apk.isolate

Index: content/content_shell_test_apk.isolate
diff --git a/content/content_shell_test_apk.isolate b/content/content_shell_test_apk.isolate
new file mode 100644
index 0000000000000000000000000000000000000000..573ac3862eecad3877fe4bc4edbe8b391055c62e
--- /dev/null
+++ b/content/content_shell_test_apk.isolate
@@ -0,0 +1,14 @@
+# Copyright (c) 2014 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.
+{
+  'conditions': [
+    ['OS=="android"', {
+      'variables': {
+        'isolate_dependency_untracked': [
+          '<(DEPTH)/content/test/data/android/device_files/',
+        ],
+      },
+    }],
+  ],
+}