android_webview: Build against NDK prebuilts, not system libraries.

build/config/compiler/BUILD.gn

 # Copyright (c) 2013 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")
 if (cpu_arch == "arm") {
   import("//build/config/arm.gni")
 }
 if (is_posix) {
   import("//build/config/gcc/gcc_version.gni")
@@ skipping 440 matching lines @@
       "-Wl,--warn-shared-textrel",
       "-nostdlib",
     ]
 
     # NOTE: The stlport header include paths below are specified in cflags
     # rather than include_dirs because they need to come after include_dirs.
     # Think of them like system headers, but don't use '-isystem' because the
     # arm-linux-androideabi-4.4.3 toolchain (circa Gingerbread) will exhibit
     # strange errors. The include ordering here is important; change with
     # caution.
-    if (use_system_stlport) {
-      cflags += [
-        # For libstdc++/include, which is used by stlport.
-        "-I" + rebase_path("$android_src/bionic", root_build_dir),
-        "-I" + rebase_path("$android_src/external/stlport/stlport",
-                           root_build_dir),
-      ]
-      libs += [
-        "stlport",
-      ]
+    android_stlport_root = "$android_ndk_root/sources/cxx-stl/stlport"
+
+    cflags += [
+      "-isystem" + rebase_path("$android_stlport_root/stlport",
+                               root_build_dir)
+    ]
+    lib_dirs += [ "$android_stlport_root/libs/$android_app_abi" ]
+
+    if (component_mode == "shared_library") {
+      libs += [ "stlport_shared" ]
     } else {
-      android_stlport_root = "$android_ndk_root/sources/cxx-stl/stlport"
-
-      cflags += [
-        "-isystem" + rebase_path("$android_stlport_root/stlport",
-                                 root_build_dir)
-      ]
-      lib_dirs += [ "$android_stlport_root/libs/$android_app_abi" ]
-
-      if (component_mode == "shared_library") {
-        libs += [ "stlport_shared" ]
-      } else {
-        libs += [ "stlport_static" ]
-      }
+      libs += [ "stlport_static" ]
     }
 
     if (cpu_arch == "mipsel") {
       libs += [
         # ld linker is used for mips Android, and ld does not accept library
         # absolute path prefixed by "-l"; Since libgcc does not exist in mips
         # sysroot the proper library will be linked.
         # TODO(gordanac): Remove once gold linker is used for mips Android.
         "gcc",
       ]
@@ skipping 448 matching lines @@
       cflags += [ "-gsplit-dwarf" ]
     }
   }
 }
 
 config("no_symbols") {
   if (!is_win) {
     cflags = [ "-g0" ]
   }
 }