Refine //extensions DEPS on //ui

extensions/DEPS

 include_rules = [
   # Do not add Chrome dependencies. Much work went into removing them.
   "+components/crx_file",
   "+components/url_matcher",
   "-content",
   "+content/grit/content_resources.h",
   "+content/public/common",
   "+content/public/test",
   "+crypto",
   "-extensions/components",
   "+extensions/test",
   "+grit/extensions_renderer_resources.h",
   "+grit/extensions_resources.h",
   "+mojo/public",
   "+testing",
-  "+ui",
+
+  # Minimal UI dependencies. There are two good rules for UI dependencies here:
+  #
+  #   1) UI components should only be added as they are needed, and
+  #   2) if //content doesn't allow it, //extensions probably won't allow it.
+  #      (see for example ui/views)
+  "-ui",
+  "+ui/base",
+  "+ui/gfx",
+  "+ui/events",
 
   # NOTE: Please do not add includes without talking to the app shell team;
   # see OWNERS for this directory.
 ]
 
 specific_include_rules = {
   ".*(test|test_util)\.(cc|h)$": [
     "+content/public/test",
 
     # Temporarily allowed testing includes.  See above.
@@ skipping 10 matching lines @@
     "+chrome/browser/extensions/test_extension_dir.h",
     "+chrome/browser/extensions/test_extension_prefs.h",
     "+chrome/browser/extensions/test_extension_system.h",
     "+chrome/browser/ui/browser.h",
     "+chrome/common/chrome_paths.h",
     "+chrome/common/extensions/features/feature_channel.h",
     "+chrome/test/base/testing_profile.h",
     "+chrome/test/base/ui_test_utils.h",
   ],
 }