Reland: [infra] Roll clang toolchain forward

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/sysroot.gni")  # Imports android/config.gni.
 import("//build/toolchain/ccache.gni")
 import("//build/toolchain/clang.gni")
 import("//build/toolchain/goma.gni")
 import("//build/toolchain/gcc_toolchain.gni")
 
@@ skipping 29 matching lines @@
       assert(!use_ccache, "Goma and ccache can't be used together.")
       compiler_prefix = "$goma_dir/gomacc "
     } else if (use_ccache) {
       compiler_prefix = "ccache "
     } else {
       compiler_prefix = ""
     }
 
     is_clang = invoker.is_clang
     if (is_clang) {
-      host_suffix = ""
-      if (host_os == "linux") {
-        host_suffix = "x86_64-linux"
-      } else if (host_os == "mac") {
-        host_suffix = "x86_64-darwin"
-      } else {
-        assert(false, "Unknown host")
-      }
-
-      prefix = rebase_path("//buildtools/toolchain/clang+llvm-$host_suffix/bin",
-                           root_build_dir)
+      prefix =
+          rebase_path("//buildtools/${host_os}-x64/clang/bin", root_build_dir)
 
       cc = compiler_prefix + prefix + "/clang"
       cxx = compiler_prefix + prefix + "/clang++"
       ar = prefix + "/llvm-ar"
     } else {
       cc = compiler_prefix + tool_prefix + "gcc"
       cxx = compiler_prefix + tool_prefix + "g++"
       ar = tool_prefix + "ar"
     }
 
@@ skipping 69 matching lines @@
   toolchain_cpu = "x86_64"
 }
 
 android_gcc_toolchains_helper("arm64") {
   android_ndk_sysroot = "$android_ndk_root/$arm64_android_sysroot_subdir"
   android_ndk_lib_dir = "usr/lib"
 
   tool_prefix = "$arm64_android_toolchain_root/bin/aarch64-linux-android-"
   toolchain_cpu = "aarch64"
 }