Pull in Chromium dependencies from HEAD

pipa/build/gitdeps.py

Index: pipa/build/gitdeps.py
diff --git a/pipa/build/gitdeps.py b/pipa/build/gitdeps.py
index 605a7112a757fc2c3ba44d8048ebce71f52731cf..0d97843e768eae5944ea5ce420a6a1f82fd7d5af 100644
--- a/pipa/build/gitdeps.py
+++ b/pipa/build/gitdeps.py
@@ -274,11 +274,34 @@ def _GetGitOrigin(path):
   return None
 
 
-def _GetGitHead(path):
-  """Returns the hash of the head of the git repo in |path|. Raises an IOError
-  if |path| doesn't exist or is not a git repo.
+def _GetGitHead(repo):
+  """Returns the hash of the head of the git repo local checkout.
+
+  Raises:
+    IOError: if repo's checkout directory doesn't exist or not a git repository.
+  """
+  with open(os.path.join(repo.checkout_dir, '.git', 'HEAD'), 'rb') as head:
+    return head.read().strip()
+
+
+def _GetGitFetchHead(repo):
+  """Returns the hash of the latest fetched revision.
+
+  Raises:
+    IOError: if repo's checkout directory doesn't exist or not a git repository.
+    KeyError: if the fetched head of the remote repository is not found in the
+      local checkout.
   """
-  return open(os.path.join(path, '.git', 'HEAD'), 'rb').read().strip()
+  path = os.path.join(repo.checkout_dir, '.git', 'FETCH_HEAD')
+  with open(path, 'rb') as heads_file:
+    for line in heads_file.readlines():
+      if not line.strip():
+        continue
+      head, repo_url = line.strip().split()
+      if repo_url == repo.repository:
+        return head
+  raise KeyError('Did not find fetched head for %s in %s' %
+                 (repo.repository, path))
 
 
 def _NormalizeGitPath(path):
@@ -390,21 +413,24 @@ def _UpdateCheckout(path, repo, dry_run):
   |dry_run| is False.
   """
   try:
-    # Try a checkout first. If this fails then we'll actually need to fetch
-    # the revision.
-    _LOGGER.info('Trying to checkout revision %s.', repo.revision)
-    _Shell('git', 'checkout', repo.revision, cwd=path,
-          dry_run=dry_run)
-    return
+    # If the repo has a revision specified, try a checkout first. If this fails
+    # then we'll actually need to fetch.
+    if _GIT_SHA1_RE.match(repo.revision):
+      _LOGGER.info('Trying to checkout revision %s.', repo.revision)
+      _Shell('git', 'checkout', repo.revision, cwd=path,
+            dry_run=dry_run)
+      return
   except RuntimeError:
     pass
 
   # Fetch the revision and then check it out. Let output go to screen rather
   # than be buffered.
-  _LOGGER.info('Fetching and checking out revision %s.', repo.revision)
+  _LOGGER.info('Fetching revision %s.', repo.revision)
   _Shell('git', 'fetch', '--depth=1', 'origin', repo.revision,
          cwd=path, dry_run=dry_run, stdout=None, stderr=None)
-  _Shell('git', 'checkout', repo.revision, cwd=path,
+  new_rev = _GetGitFetchHead(repo) if repo.revision == 'HEAD' else repo.revision
+  _LOGGER.info('Checking out revision %s.', new_rev)
+  _Shell('git', 'checkout', new_rev, cwd=path,
          dry_run=dry_run, stdout=None, stderr=None)
 
 
@@ -515,7 +541,7 @@ def _InstallRepository(options, repo):
         create_checkout = False
 
         # Get the checked out revision.
-        revhash = _GetGitHead(repo.checkout_dir)
+        revhash = _GetGitHead(repo)
         if revhash == repo.revision:
           _LOGGER.debug('Checkout is already up to date.')
           update_checkout = False