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

third_party/WebKit/LayoutTests/PRESUBMIT.py

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """LayoutTests/ presubmit script for Blink.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into gcl.
 """
 
@@ skipping 80 matching lines @@
     """Check if any new layout tests still use eventSender. If they do, we encourage replacing them with
        chrome.gpuBenchmarking.pointerActionSequence.
     """
     results = []
     actions = ["eventSender.touch", "eventSender.mouse", "eventSender.gesture"]
     for f in input_api.AffectedFiles():
         if f.Action() == 'A':
             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
 
 
 def CheckChangeOnUpload(input_api, output_api):
     results = []
     results.extend(_CheckTestharnessResults(input_api, output_api))
     results.extend(_CheckIdenticalFiles(input_api, output_api))
     results.extend(_CheckFilesUsingEventSender(input_api, output_api))
     return results
 
 
 def CheckChangeOnCommit(input_api, output_api):
     results = []
     results.extend(_CheckTestharnessResults(input_api, output_api))
     results.extend(_CheckIdenticalFiles(input_api, output_api))
     results.extend(_CheckFilesUsingEventSender(input_api, output_api))
     return results