dependency: prefer sysroot in GetBuildDependencyGraphRequest

Also freshen API python bindings.

BUG=chromium:1081828, chromium:1053703
TEST=unit tests pass

Cq-Depend: chromium:2197281
Change-Id: I27b98a40b4dbc6197c8a07fc1098c5c45ebc4be6
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2197226
Tested-by: LaMont Jones <lamontjones@chromium.org>
Commit-Queue: LaMont Jones <lamontjones@chromium.org>
Reviewed-by: Alex Klein <saklein@chromium.org>
Reviewed-by: Sean Abraham <seanabraham@chromium.org>
diff --git a/api/controller/dependency_unittest.py b/api/controller/dependency_unittest.py
index 34758c6..9e97b78 100644
--- a/api/controller/dependency_unittest.py
+++ b/api/controller/dependency_unittest.py
@@ -30,6 +30,7 @@
     self.response = depgraph_pb2.GetBuildDependencyGraphResponse()
     self.json_deps = {
         'target_board': 'deathstar',
+        'sysroot_path': '/build/deathstar',
         'package_deps': {
             'commander/darthvader-1.49.3.3': {
                 'action': 'merge',
@@ -120,7 +121,7 @@
                                        self.api_config)
     self.assertEqual(self.response.dep_graph.build_target.name, 'deathstar')
     pkg_to_cpv.assert_called_once_with(package)
-    get_dep.assert_called_once_with('target', [pkg_mock])
+    get_dep.assert_called_once_with('/build/target', 'target', [pkg_mock])
 
   def testValidateOnly(self):
     """Sanity check that a validate only call does not execute any logic."""