Android gtest runner: Add --enable-concurrent-adb flag

build/config/android/internal_rules.gni

 # Copyright 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.
 
 import("//build/config/android/config.gni")
 import("//build/config/zip.gni")
 import("//third_party/ijar/ijar.gni")
 
 assert(is_android)
 
@@ skipping 1660 matching lines @@
         "--isolate-file-path",
         rebase_path(invoker.isolate_file, root_build_dir),
       ]
     }
     if (defined(invoker.incremental_install) && invoker.incremental_install) {
       test_runner_args += [ "--incremental-install" ]
 
       # These can still be overridden, but make more better defaults during
       # development.
       test_runner_args += [
+        "--enable-concurrent-adb",
         "--enable-device-cache",
         "--num_retries=0",
       ]
     }
 
     generated_script = "$root_build_dir/bin/run_${_test_name}"
     outputs = [
       depfile,
       generated_script,
     ]
     args = [
       "--depfile",
       rebase_path(depfile, root_build_dir),
       "--script-output-path",
       rebase_path(generated_script, root_build_dir),
     ]
     args += test_runner_args
   }
 }