[Android] Add a gtest test instance for the test runner's platform mode.

build/android/pylib/base/test_instance_factory.py

Index: build/android/pylib/base/test_instance_factory.py
diff --git a/build/android/pylib/base/test_instance_factory.py b/build/android/pylib/base/test_instance_factory.py
index 9f62278f51c0f39d7e963dd5cf59a9dbdb263aac..5204b2e1d5bd5b37578b0d282aababea22e1d6a9 100644
--- a/build/android/pylib/base/test_instance_factory.py
+++ b/build/android/pylib/base/test_instance_factory.py
@@ -2,10 +2,17 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+from pylib import constants
+from pylib.gtest import gtest_test_instance
+from pylib.utils import isolator
 
-def CreateTestInstance(_args, error_func):
 
-  # TODO(jbudorick) Add gtest test instance.
+def CreateTestInstance(args, error_func):
+
+  if args.command == 'gtest':
+    return gtest_test_instance.GtestTestInstance(
+        args, isolator.Isolator(constants.ISOLATE_DEPS_DIR))
   # TODO(jbudorick) Add instrumentation test instance.
-  error_func('No test instances currently supported.')
+
+  error_func('Unable to create %s test instance.' % args.command)