[Android] Refactor browser test execution.

build/android/test_runner.py

Index: build/android/test_runner.py
diff --git a/build/android/test_runner.py b/build/android/test_runner.py
index 2cff5f25e2f3ead5d057eade47337ddac1f0698b..c69b531b8ed3389d6ae37931cdc08d355ab4736b 100755
--- a/build/android/test_runner.py
+++ b/build/android/test_runner.py
@@ -27,6 +27,8 @@ from pylib.base import test_run_factory
 from pylib.device import device_errors
 from pylib.device import device_utils
 from pylib.gtest import gtest_config
+# TODO(jbudorick): Remove this once we stop selectively enabling platform mode.
+from pylib.gtest import gtest_test_instance
 from pylib.gtest import setup as gtest_setup
 from pylib.gtest import test_options as gtest_test_options
 from pylib.linker import setup as linker_setup
@@ -919,6 +921,8 @@ def RunTestsCommand(args, parser):
     raise Exception('Failed to reset test server port.')
 
   if command == 'gtest':
+    if args.suite_name[0] in gtest_test_instance.BROWSER_TEST_SUITES:
+      return RunTestsInPlatformMode(args, parser)
     return _RunGTests(args, devices)
   elif command == 'linker':
     return _RunLinkerTests(args, devices)