presubmit: Add owners_client to presubmit API.

So that presubmit API can use it to check owners
approval.

Change-Id: Ie26c8a83de02b750fd92b4f419fe4d55809e6dbd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2621745
Reviewed-by: Gavin Mak <gavinmak@google.com>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
Auto-Submit: Edward Lesmes <ehmaldonado@chromium.org>

presubmit_support.py

@@ -43,7 +43,8 @@ import gclient_paths  # Exposed through the API
 import gclient_utils
 import git_footers
 import gerrit_util
-import owners
+import owners as owners_db
+import owners_client
 import owners_finder
 import presubmit_canned_checks
 import rdb_wrapper
@@ -651,8 +652,10 @@ class InputApi(object):
 
     # TODO(dpranke): figure out a list of all approved owners for a repo
     # in order to be able to handle wildcard OWNERS files?
-    self.owners_db = owners.Database(change.RepositoryRoot(),
+    self.owners_client = owners_client.DepotToolsClient(
-                                     fopen=open, os_path=self.os_path)
+        change.RepositoryRoot(), change.UpstreamBranch(), os_path=self.os_path)
+    self.owners_db = owners_db.Database(
+        change.RepositoryRoot(), fopen=open, os_path=self.os_path)
     self.owners_finder = owners_finder.OwnersFinder
     self.verbose = verbose
     self.Command = CommandData
@@ -1096,6 +1099,10 @@ class Change(object):
         for action, path in files
     ]
 
+  def UpstreamBranch(self):
+    """Returns the upstream branch for the change."""
+    return self._upstream
+
   def Name(self):
     """Returns the change name."""
     return self._name

tests/presubmit_unittest.py

@@ -165,6 +165,8 @@ index fe3de7b..54ae6e1 100755
         self.issue = 0
       def RepositoryRoot(self):
         return self._root
+      def UpstreamBranch(self):
+        return 'upstream'
 
     presubmit._ASKED_FOR_FEEDBACK = False
     self.fake_root_dir = self.RootDir()