Roll clang 274369:277962.

tools/clang/scripts/update.py

Index: tools/clang/scripts/update.py
diff --git a/tools/clang/scripts/update.py b/tools/clang/scripts/update.py
index 520903da26edbcb221866d9224268d27b6cc97a6..5cdfbae506b8ffb0b69a313f85991c81478adfc7 100755
--- a/tools/clang/scripts/update.py
+++ b/tools/clang/scripts/update.py
@@ -27,7 +27,7 @@ import zipfile
 # Do NOT CHANGE this if you don't know what you're doing -- see
 # https://chromium.googlesource.com/chromium/src/+/master/docs/updating_clang.md
 # Reverting problematic clang rolls is safe, though.
-CLANG_REVISION = '274369'
+CLANG_REVISION = '277962'
 
 use_head_revision = 'LLVM_FORCE_HEAD_REVISION' in os.environ
 if use_head_revision:
@@ -71,7 +71,7 @@ BINUTILS_BIN_DIR = os.path.join(BINUTILS_DIR, BINUTILS_DIR,
                                 'Linux_x64', 'Release', 'bin')
 BFD_PLUGINS_DIR = os.path.join(BINUTILS_DIR, 'Linux_x64', 'Release',
                                'lib', 'bfd-plugins')
-VERSION = '3.9.0'
+VERSION = '4.0.0'
 ANDROID_NDK_DIR = os.path.join(
     CHROMIUM_DIR, 'third_party', 'android_tools', 'ndk')
 
@@ -854,11 +854,6 @@ def main():
       print 'Skipping Clang update (make_clang_dir= was set in GYP_DEFINES).'
       return 0
 
-  if use_head_revision:
-    # TODO(hans): Remove after the next roll.
-    global VERSION
-    VERSION = '4.0.0'
-
   global CLANG_REVISION, PACKAGE_VERSION
   if args.print_revision:
     if use_head_revision or args.llvm_force_head_revision: