Add presubmit check to prevent further changes to webrtc/base.

R=mbonadei@webrtc.org
TBR=kjellander@webrtc.org
NOTRY=True
BUG=webrtc:7634

Review-Url: https://codereview.webrtc.org/2972363002
Cr-Commit-Position: refs/heads/master@{#18951}

PRESUBMIT.py

@@ -510,6 +510,24 @@ def _CheckUsageOfGoogleProtobufNamespace(input_api, output_api):
   return []
 
 
+def _CheckNoChangesToWebRTCBase(input_api, output_api):
+  """Checks that no changes refer to webrtc/base."""
+  problems = []
+
+  for f in input_api.AffectedFiles():
+    if os.path.join('webrtc', 'base') in f.LocalPath():
+      problems.append('    ' + f.LocalPath())
+      continue
+    for line_num, line in f.ChangedContents():
+      if 'webrtc/base' in line:
+        problems.append('    %s: %s' % (f.LocalPath(), line_num))
+
+  return [output_api.PresubmitPromptWarning(
+      'webrtc/base is being moved to webrtc/rtc_base (See '
+      'bugs.webrtc.org/7634). Please refer to webrtc/rtc_base instead in the '
+      'following files:\n' + '\n'.join(problems))]
+
+
 def _CommonChecks(input_api, output_api):
   """Checks common to both upload and commit."""
   results = []
@@ -578,6 +596,7 @@ def _CommonChecks(input_api, output_api):
   results.extend(_CheckUsageOfGoogleProtobufNamespace(input_api, output_api))
   results.extend(_CheckOrphanHeaders(input_api, output_api))
   results.extend(_CheckNewLineAtTheEndOfProtoFiles(input_api, output_api))
+  results.extend(_CheckNoChangesToWebRTCBase(input_api, output_api))
   return results