[Findit] Fetch DEPS from buildspec/ instead of trunk for chrome official builds.

appengine/findit/common/git_repository.py

Index: appengine/findit/common/git_repository.py
diff --git a/appengine/findit/common/git_repository.py b/appengine/findit/common/git_repository.py
index a1fb155b28606fbc067ee7988e9f5548ccb135f2..0d786578238d9353eebb77da7844a3b53af1a618 100644
--- a/appengine/findit/common/git_repository.py
+++ b/appengine/findit/common/git_repository.py
@@ -257,3 +257,11 @@ class GitRepository(Repository):
       changelogs.append(changelog)
 
     return changelogs
+
+  def GetRevisionForChromeVersion(self, version):
+    """Gets the githash revision of a chrome version."""
+    changelog = self.GetChangeLog(version)
+    if not changelog:
+      return None
+
+    return changelog.revision