[depot_tools] Find, upload and apply patchset dependencies

git_cl.py

Index: git_cl.py
diff --git a/git_cl.py b/git_cl.py
index f7192541f8769d793df98a84dbf2b10c288964ac..288e281b1170aa16220eb5fe6527f638dc1d6b5d 100755
--- a/git_cl.py
+++ b/git_cl.py
@@ -2185,6 +2185,28 @@ def RietveldUpload(options, args, cl, change):
     if target_ref:
       upload_args.extend(['--target_ref', target_ref])
 
+    # Look for dependent patchsets. See crbug.com/480453 for more details.
+    remote, upstream_branch = cl.FetchUpstreamTuple(cl.GetBranch())
+    upstream_branch = ShortBranchName(upstream_branch)
+    if remote is '.':
+      # A local branch is being tracked.
+      local_branch = ShortBranchName(upstream_branch)
+      auth_config = auth.extract_auth_config_from_options(options)
+      branch_cl = Changelist(branchref=local_branch, auth_config=auth_config)
+      branch_cl_issue_url = branch_cl.GetIssueURL()
+      branch_cl_issue = branch_cl.GetIssue()
+      branch_cl_patchset = branch_cl.GetPatchset()
+      if branch_cl_issue_url and branch_cl_issue and branch_cl_patchset:
+        upload_args.extend(
+            ['--depends_on_patchset', '%s:%s' % (
+                 branch_cl_issue, branch_cl_patchset)])
+        print
+        print ('The current branch (%s) is tracking a local branch (%s) with '
+               'an open CL.') % (cl.GetBranch(), local_branch)
+        print 'Adding %s/#ps%s as a dependency patchset.' % (
+            branch_cl_issue_url, branch_cl_patchset)
+        print
+
   project = settings.GetProject()
   if project:
     upload_args.extend(['--project', project])