Add a doc in the presubmit script checking if layout tests use eventSender

third_party/WebKit/LayoutTests/PRESUBMIT.py

Index: third_party/WebKit/LayoutTests/PRESUBMIT.py
diff --git a/third_party/WebKit/LayoutTests/PRESUBMIT.py b/third_party/WebKit/LayoutTests/PRESUBMIT.py
index ca7b4f986f0f2f6355e4740ab46787a44503aa97..1f2e4f361b6814968d013219e7683a0a4bf909af 100644
--- a/third_party/WebKit/LayoutTests/PRESUBMIT.py
+++ b/third_party/WebKit/LayoutTests/PRESUBMIT.py
@@ -98,8 +98,9 @@ def _CheckFilesUsingEventSender(input_api, output_api):
             for line_num, line in f.ChangedContents():
                 if any(action in line for action in actions):
                     results.append(output_api.PresubmitError(
-                        'Files that still use eventSender: %s:%d %s, please use chrome.gpuBenchmarking.pointerActionSequence instead.' %
-                        (f.LocalPath(), line_num, line)))
+                        'eventSender is deprecated, please use chrome.gpuBenchmarking.pointerActionSequence instead ' +
+                        '(see https://crbug.com/711340 and http://goo.gl/BND75q).\n' +
+                        'Files: %s:%d %s ' % (f.LocalPath(), line_num, line)))
     return results