Add link to Gold trybot runs in every uploaded Skia CL

PRESUBMIT.py

Index: PRESUBMIT.py
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index e91a2229b97f6bdb48788b9f4f52e2c8d36c6dde..326caad1e8a1fbd915a158ba127ceca2cf6640ff 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -36,6 +36,8 @@ PUBLIC_API_OWNERS = (
 AUTHORS_FILE_NAME = 'AUTHORS'
 
 DOCS_PREVIEW_URL = 'https://skia.org/?cl='
+GOLD_TRYBOT_URL = ('https://gold.skia.org/search2?unt=true'
+                   '&query=source_type%3Dgm&master=false&issue=')
 
 # Path to CQ bots feature is described in https://bug.skia.org/4364
 PATH_PREFIX_TO_EXTRA_TRYBOTS = {
@@ -347,6 +349,7 @@ def PostUploadHook(cl, change, output_api):
   """git cl upload will call this hook after the issue is created/modified.
 
   This hook does the following:
+  * Adds a link to the CL's Gold trybot results.
   * Adds a link to preview docs changes if there are any docs changes in the CL.
   * Adds 'NOTRY=true' if the CL contains only docs changes.
   * Adds 'NOTREECHECKS=true' for non master branch changes since they do not
@@ -377,6 +380,15 @@ def PostUploadHook(cl, change, output_api):
     original_description = rietveld_obj.get_description(issue)
     new_description = original_description
 
+    # Add GOLD_TRYBOT_URL if it does not exist yet.
+    if not re.search(r'^GOLD_TRYBOT_URL=', new_description, re.M | re.I):
+      new_description += '\nGOLD_TRYBOT_URL= %s%s' % (GOLD_TRYBOT_URL, issue)
+      results.append(
+          output_api.PresubmitNotifyResult(
+              'Added link to Gold trybot runs to the CL\'s description.\n'
+              'Note: Results may take sometime to be populated after trybots '
+              'complete.'))
+
     # If the change includes only doc changes then add NOTRY=true in the
     # CL's description if it does not exist yet.
     if all_docs_changes and not re.search(