customtabs: Update the benchmark app for hidden tab benchmarking.

tools/android/customtabs_benchmark/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")
 
 android_resources("customtabs_benchmark_apk_resources") {
   resource_dirs = [ "res/" ]
   custom_package = "org.chromium.customtabs.test"
 }
 
 android_apk("customtabs_benchmark_apk") {
   java_files = [
     "java/src/org/chromium/customtabs/test/MainActivity.java",
     "java/src/org/chromium/customtabs/test/WebViewActivity.java",
   ]
   android_manifest = "java/AndroidManifest.xml"
   apk_name = "CustomTabsBenchmark"
   deps = [
     ":customtabs_benchmark_apk_resources",
+    "//third_party/android_tools:android_support_v4_java",
     "//third_party/custom_tabs_client:custom_tabs_support_java",
   ]
 }