Check Files App with web_dev_style

Changed files are checked for style errors with web_dev_style, going forward.

Bug: 778674
Test: manually tested that style errors are checked on presubmit.
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I37e05cc6fedb842ab6d5425fc167928a1ace4ba2
Reviewed-on: https://chromium-review.googlesource.com/742941Reviewed-by: Naoki Fukino <fukino@chromium.org>
Commit-Queue: Keigo Oka <oka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#516967}

ui/file_manager/PRESUBMIT.py

@@ -20,5 +20,16 @@ def CheckChangeOnCommit(input_api, output_api):
 
 
 def _CommonChecks(input_api, output_api):
-  return input_api.canned_checks.CheckPatchFormatted(input_api, output_api,
-                                                     check_js=True)
+  results = []
+  results += input_api.canned_checks.CheckPatchFormatted(input_api, output_api,
+                                                         check_js=True)
+  try:
+    import sys
+    old_sys_path = sys.path[:]
+    cwd = input_api.PresubmitLocalPath()
+    sys.path += [input_api.os_path.join(cwd, '..', '..', 'tools')]
+    from web_dev_style import presubmit_support
+    results += presubmit_support.CheckStyle(input_api, output_api)
+  finally:
+    sys.path = old_sys_path
+  return results