[Cronet] Only run tools unittests when tools have changed

These tests are slow and only relvant to tools changes so there
is no point in running them all the time. These tests fail on
Windows, so this change prevents them from interfereing with
large-scale-refactorings done on Windows that don't affect the
tools.

Bug: 871754
Cq-Include-Trybots: master.tryserver.chromium.android:android_cronet_tester;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: Iccf6042665a027efb181848508128ef435cdd22b
Reviewed-on: https://chromium-review.googlesource.com/1172918
Commit-Queue: Paul Jensen <pauljensen@chromium.org>
Reviewed-by: Misha Efimov <mef@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582995}

components/cronet/PRESUBMIT.py

@@ -72,16 +72,15 @@ def _PackageChecks(input_api, output_api):
     return []
 
 
-def _RunUnittests(input_api, output_api):
+def _RunToolsUnittests(input_api, output_api):
   return input_api.canned_checks.RunUnitTestsInDirectory(
-      input_api, output_api, '.', [ r'^.+_unittest\.py$'])
+      input_api, output_api, '.', [ r'^tools_unittest\.py$'])
 
 
 def _ChangeAffectsCronetForAndroid(change):
   """ Returns |true| if the change may affect Cronet for Android. """
 
-  for affected_file in change.AffectedFiles():
-    path = affected_file.LocalPath()
+  for path in change.LocalPaths():
     if not path.startswith(os.path.join('components', 'cronet', 'ios')):
       return True
   return False
@@ -90,23 +89,32 @@ def _ChangeAffectsCronetForAndroid(change):
 def _ChangeAffectsCronetForIos(change):
   """ Returns |true| if the change may affect Cronet for iOS. """
 
-  for affected_file in change.AffectedFiles():
-    path = affected_file.LocalPath()
+  for path in change.LocalPaths():
     if not path.startswith(os.path.join('components', 'cronet', 'android')):
       return True
   return False
 
 
+def _ChangeAffectsCronetTools(change):
+  """ Returns |true| if the change may affect Cronet tools. """
+
+  for path in change.LocalPaths():
+    if path.startswith(os.path.join('components', 'cronet', 'tools')):
+      return True
+  return False
+
+
 def CheckChangeOnUpload(input_api, output_api):
   results = []
   results.extend(_PyLintChecks(input_api, output_api))
   results.extend(_PackageChecks(input_api, output_api))
-  results.extend(_RunUnittests(input_api, output_api))
+  if _ChangeAffectsCronetTools(input_api.change):
+    results.extend(_RunToolsUnittests(input_api, output_api))
   return results
 
 
 def CheckChangeOnCommit(input_api, output_api):
-  return _RunUnittests(input_api, output_api)
+  return _RunToolsUnittests(input_api, output_api)
 
 
 def PostUploadHook(cl, change, output_api):