Add PRESUBMIT check for native API changes.

PRESUBMIT.py

Index: PRESUBMIT.py
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index a832761c89dbd05a4205729a132260d5df334b22..76314dc24101d2248cf17c1f259b30a1cbf5d91b 100755
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -14,6 +14,73 @@ import subprocess
 import sys
 
 
+NATIVE_API_DIRS = (
+  'talk/app/webrtc',
+  'webrtc',
+  'webrtc/common_audio/include',  # DEPRECATED (will go away).

[Andrew MacDonald, 2015/11/25 19:10:40]

I think there are several users of common_audio. At least something in Chromium
is depending on the wav file handling.

[kjellander_webrtc, 2015/11/25 22:16:51]

Yes, but AFAIK the plan is to get rid of that and remove it as a supported API,
that's why I put this in here (to signal that new customers shouldn't attempt to
depend on it).

[Andrew MacDonald, 2015/11/25 23:09:53]

OK. +aluebs for visibility as I believe beamer/ is using stuff in here. I'll let
you guys take that up off-review :-)

[aluebs-webrtc, 2015/11/25 23:54:45]

Yes, common_audio is extensively used in beamer, in particular:
* channel_buffer.h
* wav_file.h
* lapped_transform.h
* real_fourier.h
* window_generator.h
* audio_ring_buffer.h
* audio_util.h
* fir_filter.h
But I am not sure what a sufficient reason is to add it to the NATIVE_API list.
Anyway, we can take this off-line.

[kjellander_webrtc, 2015/11/26 08:37:53]

Please discuss this with Henrik L (added to review now).

+  'webrtc/modules/audio_coding/main/include',

[Andrew MacDonald, 2015/11/25 19:10:40]

nit: Before we publish this as an "official" directory, any way we can finally
cause this legacy "main" thing to die?

[kjellander_webrtc, 2015/11/25 22:16:51]

Alright, I'll take care of this one too. I created
https://codereview.webrtc.org/1481493004/

[Andrew MacDonald, 2015/11/25 23:09:53]

Thanks! RIP main.

+  'webrtc/modules/audio_conference_mixer/include',  # DEPRECATED (will go away).
+  'webrtc/modules/audio_device/include',
+  'webrtc/modules/audio_processing/include',
+  'webrtc/modules/bitrate_controller/include',
+  'webrtc/modules/include',
+  'webrtc/modules/remote_bitrate_estimator/include',
+  'webrtc/modules/rtp_rtcp/include',
+  'webrtc/modules/rtp_rtcp/source',  # DEPRECATED (will go away).
+  'webrtc/modules/utility/include',
+  'webrtc/modules/video_coding/codecs/h264/include',
+  'webrtc/modules/video_coding/codecs/i420/include',
+  'webrtc/modules/video_coding/codecs/vp8/include',
+  'webrtc/modules/video_coding/codecs/vp9/include',
+  'webrtc/modules/video_coding/include',
+  'webrtc/system_wrappers/include',
+  'webrtc/voice_engine/include',
+)
+
+
+def _VerifyNativeApiHeadersListIsValid(input_api, output_api):
+  """Ensures the list of native API header directories is up to date."""
+  non_existing_paths = []
+  native_api_full_paths = [
+      input_api.os_path.join(input_api.PresubmitLocalPath(),
+                             *path.split('/')) for path in NATIVE_API_DIRS]
+  for path in native_api_full_paths:
+    if not os.path.isdir(path):
+      non_existing_paths.append(path)
+  if non_existing_paths:
+    return [output_api.PresubmitError(
+        'Directories to native API headers have changed which has made the '
+        'list in PRESUBMIT.py outdated.\nPlease update it to the current '
+        'location of our native APIs.',
+        non_existing_paths)]
+  return []
+
+
+def _CheckNativeApiHeaderChanges(input_api, output_api):
+  """Checks to remind proper changing of native APIs."""
+  files = []
+  for f in input_api.AffectedSourceFiles(input_api.FilterSourceFile):
+    if f.LocalPath().endswith('.h'):
+      for path in NATIVE_API_DIRS:
+        if os.path.dirname(f.LocalPath()) == path:
+          files.append(f)
+
+  if files:
+    return [output_api.PresubmitPromptWarning(
+        'You seem to be changing native API header files. Please make sure '
+        'you:\n'
+        '  1. Make compatible changes that doesn\'t break existing clients.\n'
+        '  2. Mark the old APIs as deprecated.\n'
+        '  3. Create a timeline and plan for when the deprecated method will '
+        'be removed.\n'
+        '  4. Update/inform existing clients to update their code to the new '

[phoglund, 2015/11/26 09:52:07]

There is really no way for anyone to know what the "existing clients" are,
either internally or externally. Should we just say "announce the change on
discuss-webrtc and remove the deprecated method after waiting at least three
months?"

[Andrew MacDonald, 2015/11/26 17:13:20]

And probably webrtc-users, since I doubt many Google internal users are
monitoring discuss-webrtc?

[kjellander_webrtc, 2015/11/27 07:06:59]

Right, I guess externals cannot post to this list anyway, so it shouldn't be a
problem.

+        'API.\n'
+        '  5. (much later) remove the deprecated API.\n'
+        'Related files:',
+        files)]
+  return []
+
+
 def _CheckNoIOStreamInHeaders(input_api, output_api):
   """Checks to make sure no .h files include <iostream>."""
   files = []
@@ -299,6 +366,7 @@ def _CommonChecks(input_api, output_api):
   results.extend(input_api.canned_checks.CheckChangeTodoHasOwner(
       input_api, output_api))
   results.extend(_CheckApprovedFilesLintClean(input_api, output_api))
+  results.extend(_CheckNativeApiHeaderChanges(input_api, output_api))
   results.extend(_CheckNoIOStreamInHeaders(input_api, output_api))
   results.extend(_CheckNoFRIEND_TEST(input_api, output_api))
   results.extend(_CheckGypChanges(input_api, output_api))
@@ -318,6 +386,7 @@ def CheckChangeOnUpload(input_api, output_api):
 def CheckChangeOnCommit(input_api, output_api):
   results = []
   results.extend(_CommonChecks(input_api, output_api))
+  results.extend(_VerifyNativeApiHeadersListIsValid(input_api, output_api))
   results.extend(input_api.canned_checks.CheckOwners(input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeWasUploaded(
       input_api, output_api))