[ChromeDriver] Detect release branch without Git

Existing ChromeDriver build script uses Git to determine if it is
built in a release branch. However, some distros build ChromeDriver from
source tarball, detached from Git repository (e.g., see
https://groups.google.com/a/chromium.org/forum/#!topic/chromium-packagers/LxpjcTrAzGA).
This CL updates the build script to handle such cases.

Change-Id: I9c59c90fc94dfa0bfebbbb83584ef7dda7153dc7
Reviewed-on: https://chromium-review.googlesource.com/c/1274894Reviewed-by: Caleb Rouleau <crouleau@chromium.org>
Commit-Queue: John Chen <johnchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#598860}

chrome/test/chromedriver/embed_version_in_cpp.py

@@ -25,6 +25,14 @@ def get_release_version(chrome_version_file, version_info):
     version_info: VersionInfo object returned from lastchange.FetchVersionInfo.
   """
 
+  # Parse Chrome version file, which should have four lines of key=value,
+  # giving the major, minor, build, and patch number.
+  version = {}
+  for line in open(chrome_version_file, 'r').readlines():
+    key, val = line.rstrip('\r\n').split('=', 1)
+    version[key] = val
+
+  if version_info is not None:
     # Release branch revision has the format
     # '26c10db8bff36a8b6fc073c0f38b1e9493cabb04-refs/branch-heads/3515@{#5}'.
     match = re.match('[0-9a-fA-F]+-refs/branch-heads/\d+@{#\d+}',
@@ -33,18 +41,19 @@ def get_release_version(chrome_version_file, version_info):
       # revision is not the expected format, probably not in a release branch.
       return None
 
-  # Parse Chrome version file, which should have four lines of key=value,
-  # giving the major, minor, build, and patch number.
-  values = {}
-  for line in open(chrome_version_file, 'r').readlines():
-    key, val = line.rstrip('\r\n').split('=', 1)
-    values[key] = val
-
     # Result is based on Chrome version number, e.g.,
     # '70.0.3516.0 (26c10db8bff36a8b6fc073c0f38b1e9493cabb04)'.
     return '%s.%s.%s.%s (%s)' % (
-      values['MAJOR'], values['MINOR'], values['BUILD'], values['PATCH'],
+        version['MAJOR'], version['MINOR'], version['BUILD'], version['PATCH'],
         version_info.revision_id)
+  else:
+    # No version_info from Git. Assume we are in a release branch if Chrome
+    # patch number is not 0.
+    if version['PATCH'] == '0':
+      return None
+
+    return '%s.%s.%s.%s' % (
+        version['MAJOR'], version['MINOR'], version['BUILD'], version['PATCH'])
 
 
 def get_master_version(chromedriver_version, version_info):
@@ -55,6 +64,9 @@ def get_master_version(chromedriver_version, version_info):
     version_info: VersionInfo object returned from lastchange.FetchVersionInfo.
   """
 
+  if version_info is None:
+    return None
+
   # Master branch revision has the format
   # 'cc009559c91323445dec7e2f545298bf10726eaf-refs/heads/master@{#581331}'.
   # We need to grab the commit position (e.g., '581331') near the end.
@@ -91,17 +103,17 @@ def main():
   # On failure, version_info is None.
   version_info = lastchange.FetchGitRevision(None, '^Change-Id:')
 
-  if version_info:
   version = get_release_version(options.chrome_version_file, version_info)
 
-    if not version:
+  if version is None:
     version = get_master_version(chromedriver_version, version_info)
 
-    if not version:
+  if version is None:
+    if version_info is not None:
       # Not in a known branch, but has Git revision.
       version = '%s (%s)' % (chromedriver_version, version_info.revision_id)
     else:
-    # Git command failed for some reason. Just use ChromeDriver version string.
+      # Git command failed. Just use ChromeDriver version string.
       version = chromedriver_version
 
   global_string_map = {