build: move libcc patches to electron repo (#14104)

In the GN build, libchromiumcontent is no longer a distinct library, but
merely a container for a set of scripts and patches. Maintaining those
patches in a separate repository is tedious and error-prone, so merge
them into the main repo.

Once this is merged and GN is the default way to build Electron, the
libchromiumcontent repository can be archived.

script/lib/git.py

@@ -0,0 +1,105 @@
+"""Git helper functions.
+
+Everything in here should be project agnostic, shouldn't rely on project's structure,
+and make any assumptions about the passed arguments or calls outcomes.
+"""
+
+import os
+import subprocess
+
+from util import scoped_cwd
+
+
+def is_repo_root(path):
+  path_exists = os.path.exists(path)
+  if not path_exists:
+    return False
+
+  git_folder_path = os.path.join(path, '.git')
+  git_folder_exists = os.path.exists(git_folder_path)
+
+  return git_folder_exists
+
+
+def get_repo_root(path):
+  """Finds a closest ancestor folder which is a repo root."""
+  norm_path = os.path.normpath(path)
+  norm_path_exists = os.path.exists(norm_path)
+  if not norm_path_exists:
+    return None
+
+  if is_repo_root(norm_path):
+    return norm_path
+
+  parent_path = os.path.dirname(norm_path)
+
+  # Check if we're in the root folder already.
+  if parent_path == norm_path:
+    return None
+
+  return get_repo_root(parent_path)
+
+
+def apply(repo, patch_path, directory=None, index=False, reverse=False):
+  args = ['git', 'apply',
+          '--ignore-space-change',
+          '--ignore-whitespace',
+          '--whitespace', 'fix'
+          ]
+  if directory:
+    args += ['--directory', directory]
+  if index:
+    args += ['--index']
+  if reverse:
+    args += ['--reverse']
+  args += ['--', patch_path]
+
+  with scoped_cwd(repo):
+    return_code = subprocess.call(args)
+    applied_successfully = (return_code == 0)
+    return applied_successfully
+
+
+def get_patch(repo, commit_hash):
+  args = ['git', 'diff-tree',
+          '-p',
+          commit_hash,
+          '--'  # Explicitly tell Git that `commit_hash` is a revision, not a path.
+          ]
+
+  with scoped_cwd(repo):
+    return subprocess.check_output(args)
+
+
+def get_head_commit(repo):
+  args = ['git', 'rev-parse', 'HEAD']
+
+  with scoped_cwd(repo):
+    return subprocess.check_output(args).strip()
+
+
+def reset(repo):
+  args = ['git', 'reset']
+
+  with scoped_cwd(repo):
+    subprocess.check_call(args)
+
+
+def commit(repo, author, message):
+  """ Commit whatever in the index is now."""
+
+  # Let's setup committer info so git won't complain about it being missing.
+  # TODO: Is there a better way to set committer's name and email?
+  env = os.environ.copy()
+  env['GIT_COMMITTER_NAME'] = 'Anonymous Committer'
+  env['GIT_COMMITTER_EMAIL'] = 'anonymous@electronjs.org'
+
+  args = ['git', 'commit',
+          '--author', author,
+          '--message', message
+          ]
+
+  with scoped_cwd(repo):
+    return_code = subprocess.call(args, env=env)
+    committed_successfully = (return_code == 0)
+    return committed_successfully