Add PRESUBMIT script to enforce WebAPK shell apk version update

This CL adds PRESUBMIT script to chrome/android/webapk/shell_apk so
that any time code in chrome/android/webapk/shell_apk/ changes,
chrome/android/webapk/shell_apk/shell_apk_version.gni must be updated
accordingly. See comments in presubmit.py for detailed rules.

BUG=708053

Review-Url: https://codereview.chromium.org/2830343002
Cr-Commit-Position: refs/heads/master@{#467779}

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 shell_apk/ directory has changed (excluding test files),
+$WAM_MINT_TRIGGER_VARIABLE should be updated.
+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
+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 _DoChangedContentsContain(changed_contents, key):
+  for line_num, line in changed_contents:
+    if key in line:
+      return True
+  return False
+
+
+def _CheckChromeUpdateTriggerRule(input_api, output_api):
+  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:
+      if _DoChangedContentsContain(f.ChangedContents(),
+                                 CHROME_UPDATE_TRIGGER_VARIABLE):
+        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_update_needed = False
+  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_update_needed = True
+      problems.append(local_path)
+    elif local_path == SHELL_APK_VERSION_LOCAL_PATH:
+      if _DoChangedContentsContain(f.ChangedContents(),
+                                 WAM_MINT_TRIGGER_VARIABLE):
+        wam_mint_trigger_is_updated = True
+
+  if wam_mint_trigger_update_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)