Simplify caller checking logic in WebApkServiceImpl

chrome/android/webapk/libs/runtime_library/BUILD.gn

 # Copyright 2016 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")
 import("//chrome/android/webapk/libs/runtime_library_version.gni")
 
 # runtime_library_version.gni must be updated whenever the runtime library is
 # updated. The WebAPK re-extracts the runtime library from the Chrome APK when
 # |runtime_library_version| is incremented.
 
 # Whenever this constant is changed, WebApkUtils#getRuntimeDexName() must also
 # be changed.
 runtime_library_dex_asset_name = "webapk$runtime_library_version.dex"
 
 android_aidl("webapk_service_aidl") {
   import_include = "src/org/chromium/webapk/lib/runtime_library"
   interface_file = "src/org/chromium/webapk/lib/runtime_library/common.aidl"
   sources = [
     "src/org/chromium/webapk/lib/runtime_library/IWebApkApi.aidl",
   ]
 }
 
 android_library("runtime_library_java") {
-  dex_path = "$target_gen_dir/$runtime_library_dex_asset_name"
+  # The dx tool expects files ending in .dex.jar
+  dex_path = "$target_gen_dir/$runtime_library_dex_asset_name.jar"
   java_files = [
     "src/org/chromium/webapk/lib/runtime_library/HostBrowserLauncher.java",
     "src/org/chromium/webapk/lib/runtime_library/WebApkServiceImpl.java",
   ]
   srcjar_deps = [ ":webapk_service_aidl" ]
   deps = [
     "//chrome/android/webapk/libs/common:common_java",
   ]
 }
 
 android_assets("runtime_library_assets") {
   write_file("$target_gen_dir/webapk_dex_version.txt", runtime_library_version)
 
   sources = [
-    "$target_gen_dir/$runtime_library_dex_asset_name",
     "$target_gen_dir/webapk_dex_version.txt",
   ]
+  renaming_sources = [ "$target_gen_dir/$runtime_library_dex_asset_name.jar" ]
+  renaming_destinations = [ "$runtime_library_dex_asset_name" ]
   disable_compression = true
 
   deps = [
     ":runtime_library_java",
   ]
 }
 
-junit_binary("webapk_runtime_library_junit_tests") {
-  java_files = [ "junit/src/org/chromium/webapk/lib/runtime_library/WebApkServiceImplTest.java" ]
+android_library("runtime_library_javatests") {
+  testonly = true
+  java_files = [ "javatests/src/org/chromium/webapk/lib/runtime_library/WebApkServiceImplTest.java" ]
   deps = [
     ":runtime_library_java",
-    "//base:base_junit_test_support",
+    "//base:base_java_test_support",
+    "//chrome/test/android:chrome_java_test_support",
+    "//content/public/test/android:content_java_test_support",
   ]
 }