Add a custom Robolectric testrunner.

third_party/robolectric/BUILD.gn

 # Copyright 2015 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/rules.gni")
 
 # GYP: //third_party/robolectric/robolectric.gyp:android_all_jar
-java_prebuilt("android_all_java") {
+java_prebuilt("android-all-4.3_r2-robolectric-0") {
   visibility = [ ":*" ]
   jar_path = "lib/android-all-4.3_r2-robolectric-0.jar"
 }
 
 # GYP: //third_party/robolectric/robolectric.gyp:tagsoup_jar
-java_prebuilt("tagsoup_java") {
+java_prebuilt("tagsoup-1.2") {
   visibility = [ ":*" ]
   jar_path = "lib/tagsoup-1.2.jar"
 }
 
 # GYP: //third_party/robolectric/robolectric.gyp:json_jar
-java_prebuilt("json_java") {
+java_prebuilt("json-20080701") {
   visibility = [ ":*" ]
   jar_path = "lib/json-20080701.jar"
 }
 
 # GYP: //third_party/robolectric/robolectric.gyp:robolectric_jar
 java_prebuilt("robolectric_java") {
   testonly = true
   jar_path = "lib/robolectric-2.4-jar-with-dependencies.jar"
   deps = [
-    ":android_all_java",
-    ":tagsoup_java",
-    ":json_java",
+    ":android-all-4.3_r2-robolectric-0",
+    ":tagsoup-1.2",
+    ":json-20080701",
   ]
 }