Add PRESUBMIT script to enforce WebAPK shell apk version update

chrome/android/webapk/shell_apk/PRESUBMIT.py

+# Copyright (c) 2017 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.
+
+"""Presubmit script for changes affecting chrome/android/webapk/shell_apk
+
+See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
+for more details about the presubmit API built into depot_tools.
+
+This presubmit checks for two rules:
+1. If anything in $ANDROID_MANIFEST_LOCAL_PATH, $RES_LOCAL_PATH, or
+$SRC_LOCAL_PATH changes, $WAM_MINT_TRIGGER_VARIABLE in
+$SHELL_APK_VERSION_LOCAL_PATH should be changed.

[pkotwicz, 2017/04/27 15:54:30]

How about: "If anything in shell_apk/ directory has changed (excluding test
files) $WAM_MINT_TRIGGER_VARIABLE should be changed"

I think my version is more readable.

[F, 2017/04/27 18:31:56]

Done.

+2. If $CHROME_UPDATE_TIRGGER_VARIABLE is changed in
+$SHELL_APK_VERSION_LOCAL_PATH, $SHELL_APK_VERSION_LOCAL_PATH should be the
+only changed file and changing $CHROME_UPDATE_TIRGGER_VARIABLE should be

[hartmanng, 2017/04/27 15:05:54]

request: it might be good to go a step further here and ensure that when
$CHROME_UPDATE_TIRGGER_VARIABLE is updated, it must match the existing value of
$WAM_MINT_TRIGGER_VARIABLE

[F, 2017/04/27 15:58:05]

Presubmit needs to use lots of regexp to do this while I think making sure these
two variables match lies within the CL review's responsibility. So I propose
letting presubmit only handling formatting stuff. WDUT?

+the only change.
+"""
+
+WAM_MINT_TRIGGER_VARIABLE = r'template_shell_apk_version'
+CHROME_UPDATE_TRIGGER_VARIABLE = r'expected_shell_apk_version'
+
+ANDROID_MANIFEST_LOCAL_PATH = r'AndroidManifest.xml'
+RES_LOCAL_PATH = r'res/'
+SHELL_APK_VERSION_LOCAL_PATH = r'shell_apk_version.gni'
+SRC_LOCAL_PATH = r'src/org/chromium/webapk/shell_apk/'
+
+
+def _CheckChromeUpdateTriggerRule(input_api, output_api):
+  problems = []

[pkotwicz, 2017/04/27 15:54:30]

This variable is unused

[F, 2017/04/27 18:31:56]

Done.

+
+  chrome_update_trigger_is_updated = False

[pkotwicz, 2017/04/27 15:54:30]

This variable is unused

[F, 2017/04/27 18:31:56]

Done.

+  for f in input_api.AffectedFiles():
+    local_path = input_api.os_path.relpath(f.AbsoluteLocalPath(),
+                                           input_api.PresubmitLocalPath())
+
+    if local_path == SHELL_APK_VERSION_LOCAL_PATH:
+      for line_num, line in f.ChangedContents():

[pkotwicz, 2017/04/27 15:54:30]

Can you move iterating through the changed contents to a new function? This
removes some code which is duplicated in _CheckChromeUpdateTriggerRule() and
_CheckWamMintTriggerRule()

Perhaps:

def _DoesChangedContentsContain(changed_contents, search_for):

[F, 2017/04/27 18:31:56]

Done.

+        if CHROME_UPDATE_TRIGGER_VARIABLE in line:
+          if (len(f.ChangedContents) != 1 or
+              len(input_api.AffectedFiles() != 1)):
+            return [
+                output_api.PresubmitError(
+                    '{} in {} must be updated in a standalone CL.'.format(
+                        CHROME_UPDATE_TRIGGER_VARIABLE,
+                        SHELL_APK_VERSION_LOCAL_PATH))
+            ]
+
+  return []
+
+
+def _CheckWamMintTriggerRule(input_api, output_api):
+  problems = []
+
+  wam_mint_trigger_updated_needed = False

[hartmanng, 2017/04/27 15:05:54]

nit: s/updated_needed/update_needed/ (and elsewhere)

[F, 2017/04/27 15:58:05]

Done.

+  wam_mint_trigger_is_updated = False
+  for f in input_api.AffectedFiles():
+    local_path = input_api.os_path.relpath(f.AbsoluteLocalPath(),
+                                           input_api.PresubmitLocalPath())
+
+    if (local_path == ANDROID_MANIFEST_LOCAL_PATH or
+        local_path.startswith(RES_LOCAL_PATH) or
+        local_path.startswith(SRC_LOCAL_PATH)):
+      wam_mint_trigger_updated_needed = True
+      problems.append(local_path)
+    elif local_path == SHELL_APK_VERSION_LOCAL_PATH:
+      for line_num, line in f.ChangedContents():
+        if WAM_MINT_TRIGGER_VARIABLE in line:
+          wam_mint_trigger_is_updated = True
+
+  if wam_mint_trigger_updated_needed and not wam_mint_trigger_is_updated:
+    return [output_api.PresubmitError(
+        '{} in {} needs to updated due to changes in:'.format(
+            WAM_MINT_TRIGGER_VARIABLE, SHELL_APK_VERSION_LOCAL_PATH),
+        items=problems)]
+
+  return []
+
+
+def _CommonChecks(input_api, output_api):
+  """Checks common to both upload and commit."""
+  result = []
+  result.extend(_CheckChromeUpdateTriggerRule(input_api, output_api))
+  result.extend(_CheckWamMintTriggerRule(input_api, output_api))
+
+  return result
+
+
+def CheckChangeOnUpload(input_api, output_api):
+  return _CommonChecks(input_api, output_api)
+
+
+def CheckChangeOnCommit(input_api, output_api):
+  return _CommonChecks(input_api, output_api)