Add gn Blink GC plugin options

build/toolchain/android/BUILD.gn

 # Copyright 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/clang/clang.gni")
 import("//build/config/sysroot.gni")  # Imports android/config.gni.
 import("//build/toolchain/gcc_toolchain.gni")
 
 # The Android GCC toolchains share most of the same parameters, so we have this
 # wrapper around gcc_toolchain to avoid duplication of logic.
 #
 # Parameters:
 #  - toolchain_cpu
 #      Same as gcc_toolchain.
 #  - toolchain_root
@@ skipping 20 matching lines @@
     solink_libs_section_prefix = "$_ndk_lib/crtbegin_so.o"
     solink_libs_section_postfix = "$_ndk_lib/crtend_so.o"
 
     _android_tool_prefix =
         "${invoker.toolchain_root}/bin/${invoker.binary_prefix}-"
 
     # The tools should be run relative to the build dir.
     _tool_prefix = rebase_path("$_android_tool_prefix", root_build_dir)
 
     if (is_clang) {
-      _prefix = rebase_path("//third_party/llvm-build/Release+Asserts/bin",
-                            root_build_dir)
+      _prefix = rebase_path("$clang_base_path/bin", root_build_dir)
       cc = "$_prefix/clang"
       cxx = "$_prefix/clang++"
     } else {
       cc = "${_tool_prefix}gcc"
       cxx = "${_tool_prefix}g++"
     }
     ar = _tool_prefix + "ar"
     ld = cxx
     readelf = _tool_prefix + "readelf"
     nm = _tool_prefix + "nm"
@@ skipping 56 matching lines @@
   binary_prefix = "aarch64-linux-android"
 }
 
 android_gcc_toolchains_helper("mips64el") {
   toolchain_cpu = "mips64el"
   toolchain_root = mips64_android_toolchain_root
   sysroot = "$android_ndk_root/$mips64_android_sysroot_subdir"
   lib_dir = "usr/lib64"
   binary_prefix = "mips64el-linux-android"
 }