buildtools: remove libc++ from buildtools/DEPS

This is very similar to
https://chromium-review.googlesource.com/c/chromium/src/+/2729355 ,
just with libcxx instead of libcxxabi. See that CL description for
details, except here you want to add

  'libcxx_revision':       '8fa87946779682841e21e2da977eccfb6cb3bded',

and a project-appropriate version of

  'src/buildtools/third_party/libc++/trunk':
    Var('chromium_git') +
    '/external/github.com/llvm/llvm-project/libcxx.git' + '@' +
    Var('libcxx_revision'),

(...and then add this as a transitive dep of your chromium roller,
as described in that other CL, like a bunch of projects have already
done.)

Bug: 1182719,1177288
Change-Id: I1362eb591f49111143733c036548670ee4004673
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2733154
Auto-Submit: Nico Weber <thakis@chromium.org>
Commit-Queue: Dirk Pranke <dpranke@google.com>
Reviewed-by: Dirk Pranke <dpranke@google.com>
Cr-Commit-Position: refs/heads/master@{#859627}

DEPS

@@ -377,6 +377,10 @@ vars = {
   # and whatever else without interference from each other.
   'libunwind_revision':    '8869f42e7fc234f038cd78097e19e304773cc8f0',
 
+  # If you change this, also update the libc++ revision in
+  # //buildtools/deps_revisions.gni.
+  'libcxx_revision':       '8fa87946779682841e21e2da977eccfb6cb3bded',
+
   # TODO(crbug.com/941824): The values below need to be kept in sync
   # between //DEPS and //buildtools/DEPS, so if you're updating one,
   # update the other. There is a presubmit check that checks that
@@ -388,11 +392,9 @@ vars = {
   # GN CIPD package version.
   'gn_version': 'git_revision:dfcbc6fed0a8352696f92d67ccad54048ad182b3',
 
-  # Also, if you change these, update buildtools/DEPS too. Also update the
-  # libc++ svn_revision in //buildtools/deps_revisions.gni.
+  # Also, if you change these, update buildtools/DEPS too.
   # TODO(crbug.com/1166332) rename to clang_format_revision.
   'clang_fmt_revision':    '99803d74e35962f63a775f29477882afd4d57d94',
-  'libcxx_revision':       '8fa87946779682841e21e2da977eccfb6cb3bded',
 
 }
 

PRESUBMIT.py

@@ -4140,7 +4140,7 @@ def CheckBuildtoolsRevisionsAreInSync(input_api, output_api):
 
   # Update this regexp if new revisions are added to the files.
   rev_regexp = input_api.re.compile(
-      ("'((clang_format|libcxx)_revision|gn_version)':"))
+      ("'(clang_format_revision|gn_version)':"))
 
   # If a user is changing one revision, they need to change the same
   # line in both files. This means that any given change should contain

PRESUBMIT_test.py

@@ -3499,7 +3499,7 @@ def _check(self, files):
 
   def testOneFileChangedButNotTheOther(self):
     results = self._check({
-        "DEPS": "'libcxx_revision': 'onerev'",
+        "DEPS": "'gn_version': 'onerev'",
     })
     self.assertNotEqual(results, [])
 
@@ -3511,15 +3511,15 @@ def testNeitherFileChanged(self):
 
   def testBothFilesChangedAndMatch(self):
     results = self._check({
-        "DEPS": "'libcxx_revision': 'onerev'",
-        os.path.join("buildtools", "DEPS"): "'libcxx_revision': 'onerev'",
+        "DEPS": "'gn_version': 'onerev'",
+        os.path.join("buildtools", "DEPS"): "'gn_version': 'onerev'",
     })
     self.assertEqual(results, [])
 
   def testBothFilesWereChangedAndDontMatch(self):
     results = self._check({
-        "DEPS": "'libcxx_revision': 'rev1'",
-        os.path.join("buildtools", "DEPS"): "'libcxx_revision': 'rev2'",
+        "DEPS": "'gn_version': 'rev1'",
+        os.path.join("buildtools", "DEPS"): "'gn_version': 'rev2'",
     })
     self.assertNotEqual(results, [])
 

buildtools/DEPS

@@ -16,10 +16,8 @@ vars = {
   # GN CIPD package version.
   'gn_version': 'git_revision:dfcbc6fed0a8352696f92d67ccad54048ad182b3',
 
-  # When changing these, also update the svn revisions in deps_revisions.gni
   # TODO(crbug.com/1166332) rename to clang_format_revision.
   'clang_fmt_revision':    '99803d74e35962f63a775f29477882afd4d57d94',
-  'libcxx_revision':       '8fa87946779682841e21e2da977eccfb6cb3bded',
 }
 
 deps = {
@@ -47,10 +45,6 @@ deps = {
     'dep_type': 'cipd',
     'condition': 'host_os == "mac"',
   },
-  'third_party/libc++/trunk':
-    Var('chromium_url') +
-    '/external/github.com/llvm/llvm-project/libcxx.git' + '@' +
-    Var('libcxx_revision'),
   'win': {
     'packages': [
       {