Roll clang 274369:277642.

build/toolchain/toolchain.gni

 # 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.
 
 # Toolchain-related configuration that may be needed outside the context of the
 # toolchain() rules themselves.
 
 import("//build/config/chrome_build.gni")
 
 declare_args() {
   # Enable Link Time Optimization in optimized builds (output programs run
   # faster, but linking is up to 5-20x slower).
   # Note: use target_os == "linux" rather than is_linux so that it does not
   # apply to host_toolchain when target_os="android".
   allow_posix_link_time_opt =
       target_os == "linux" && !is_chromeos && target_cpu == "x64" &&
       is_chrome_branded && is_official_build
 
   # Set to true to use lld, the LLVM linker. This flag may be used on Windows
   # with the shipped LLVM toolchain, or on Linux with a self-built top-of-tree
   # LLVM toolchain (see llvm_force_head_revision in
   # build/config/compiler/BUILD.gn).
   use_lld = is_win && host_os != "win"
 
-  # If this is set to true, or if LLVM_FORCE_HEAD_REVISION is set to 1
-  # in the environment, we use the revision in the llvm repo to determine
-  # the CLANG_REVISION to use, instead of the version hard-coded into
-  # //tools/clang/scripts/update.py. This should only be used in
-  # conjunction with setting LLVM_FORCE_HEAD_REVISION in the
-  # environment when `gclient runhooks` is run as well.
-  llvm_force_head_revision = false
-
   # Compile with Xcode version of clang instead of hermetic version shipped
   # with the build. Used on iOS to ship official builds (as they are built
   # with the version of clang shipped with Xcode).
   use_xcode_clang = is_ios && is_official_build
 }
 
-declare_args() {
-  if (is_clang) {
-    # Clang compiler version. Clang files are placed at version-dependent paths.
-    clang_version = "3.9.0"
-
-    if (llvm_force_head_revision) {
-      # TODO(hans): Remove after next Clang roll.
-      # ToT Clang has a higher version number.
-      clang_version = "4.0.0"
-    }
-  }
+if (is_clang) {
+  # Clang compiler version. Clang files are placed at version-dependent paths.
+  clang_version = "4.0.0"
 }
 
 # Check target_os here instead of is_ios as this file is loaded for secondary
 # toolchain (host toolchain in particular) but the argument is the same for
 # all toolchains.
 assert(!use_xcode_clang || target_os == "ios",
        "Using Xcode's clang is only supported in iOS builds")
 
 # Subdirectory within root_out_dir for shared library files.
 # TODO(agrieve): GYP sets this to "lib" for Linux & Android, but this won't work
@@ skipping 38 matching lines @@
 stamp_description = "STAMP {{output}}"
 copy_description = "COPY {{source}} {{output}}"
 if (host_os == "win") {
   stamp_command = "$python_path gyp-win-tool stamp {{output}}"
   copy_command =
       "$python_path gyp-win-tool recursive-mirror {{source}} {{output}}"
 } else {
   stamp_command = "touch {{output}}"
   copy_command = "ln -f {{source}} {{output}} 2>/dev/null || (rm -rf {{output}} && cp -af {{source}} {{output}})"
 }