Move PrefMember and PrefChangeRegistrar to api directory.

chrome/browser/autofill/DEPS

 include_rules = [
   # Autofill is being made into a Browser Component, so we have these
   # three basic rules followed by temporary exceptions.  Please don't
   # add to the list of exceptions!
   "-chrome/browser",
   "+chrome/browser/api",
   "+chrome/browser/autofill",
 
   # Permanently-allowed DEPS beyond the standard Browser
   # Components-like DEPS above go here.
   "+third_party/libphonenumber",  # For phone number i18n.
 
   # TODO(joi): Bring this list to zero.
   #
   # Do not add to the list of temporarily-allowed dependencies below,
   # and please do not introduce more #includes of these files.
   "!chrome/browser/password_manager/password_manager.h",
-  "!chrome/browser/prefs/pref_change_registrar.h",
-  "!chrome/browser/prefs/pref_member.h",
   "!chrome/browser/prefs/pref_service.h",
   "!chrome/browser/profiles/profile.h",
   "!chrome/browser/profiles/profile_dependency_manager.h",
   "!chrome/browser/profiles/profile_keyed_service.h",
   "!chrome/browser/profiles/profile_keyed_service_factory.h",
   "!chrome/browser/sync/profile_sync_service.h",
   "!chrome/browser/sync/profile_sync_service_factory.h",
   "!chrome/browser/sync/profile_sync_service_observer.h",
   "!chrome/browser/ui/browser.h",
   "!chrome/browser/ui/browser_finder.h",
@@ skipping 16 matching lines @@
   # Do not add to the list of temporarily-allowed dependencies below,
   # and please do not introduce more #includes of these files.
   '.*_[a-z]*test\.cc': [
     "!chrome/browser/password_manager/encryptor.h",
     "!chrome/browser/translate/translate_infobar_delegate.h",
     "!chrome/browser/translate/translate_manager.h",
     "!chrome/browser/ui/browser_tabstrip.h",
     "!chrome/browser/ui/tab_contents/test_tab_contents.h",
   ]
 }