android_webview: Build against NDK prebuilts, not system libraries.

build/config/android/config.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.
 
 # This file contains common system config stuff for the Android build.
 
 if (is_android) {
   declare_args() {
     # Absolute directory containing the Android source code.
     android_src = ""
@@ skipping 101 matching lines @@
       "$android_toolchain_root/lib/gcc/mipsel-linux-android/${_android_toolchain_version}/libgcc.a"
   } else {
     assert(false, "Need android libgcc support for your target arch.")
   }
 
   android_readelf = "$android_toolchain_root/bin/$_binary_prefix-readelf"
   android_gdbserver = "$android_ndk_root/prebuilt/$android_prebuilt_arch/gdbserver/gdbserver"
 
   # stlport stuff --------------------------------------------------------------
 
-  use_system_stlport = is_android_webview_build
-
-  if (use_system_stlport) {
-    android_stlport_library = "stlport"
-  } else if (component_mode == "shared_library") {
+  if (component_mode == "shared_library") {
     android_stlport_library = "stlport_shared"
   } else {
     android_stlport_library = "stlport_static"
   }
 
   # ABI ------------------------------------------------------------------------
 
   if (cpu_arch == "x86") {
     android_app_abi = "x86"
   } else if (cpu_arch == "arm") {
     import("//build/config/arm.gni")
     if (arm_version < 7) {
       android_app_abi = "armeabi"
     } else {
       android_app_abi = "armeabi-v7a"
     }
   } else if (cpu_arch == "mipsel") {
     android_app_abi = "mips"
   } else {
     assert(false, "Unknown Android ABI: " + cpu_arch)
   }
 } else {
   if (!defined(is_android_webview_build)) {
     is_android_webview_build = false
   }
-  use_system_stlport = false
 }