Purge the App Launcher code from Mac

It hasn't been compiled for 1 milestone (since r394856).

BUG=600915

Review-Url: https://codereview.chromium.org/2131463002
Cr-Commit-Position: refs/heads/master@{#404275}
diff --git a/ui/app_list/PRESUBMIT.py b/ui/app_list/PRESUBMIT.py
index 73df615..e788678 100644
--- a/ui/app_list/PRESUBMIT.py
+++ b/ui/app_list/PRESUBMIT.py
@@ -12,14 +12,9 @@
   r'.*\.(cc|h)$',
 )
 
-EXCLUDE = (
-  # Objective C confuses everything.
-  r'.*/cocoa/.*',
-)
-
 def CheckChangeLintsClean(input_api, output_api):
   """Makes sure that the ui/app_list/ code is cpplint clean."""
-  black_list = input_api.DEFAULT_BLACK_LIST + EXCLUDE
+  black_list = input_api.DEFAULT_BLACK_LIST
   sources = lambda x: input_api.FilterSourceFile(
     x, white_list = INCLUDE_CPP_FILES_ONLY, black_list = black_list)
   return input_api.canned_checks.CheckChangeLintsClean(