components: Fix 'gn check' errors for omnibox.

components/sessions/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 if (is_android) {
   import("//build/config/android/config.gni")
 }
 
 config("implementation") {
   defines = [ "SESSIONS_IMPLEMENTATION" ]
@@ skipping 33 matching lines @@
       ":shared",
       "//base",
 
       # '../ios/web/ios_web.gyp:ios_web',  TODO(GYP) iOS.
     ]
   }
 }
 
 # Sources shared between the content and iOS implementations.
 source_set("shared") {
-  visibility = [ ":*" ]
-
   sources = [
     "base_session_service.cc",
     "base_session_service.h",
     "base_session_service_commands.cc",
     "base_session_service_commands.h",
     "base_session_service_delegate.h",
     "core/serialized_navigation_driver.h",
     "serialized_navigation_entry.cc",
     "serialized_navigation_entry.h",
     "session_backend.cc",
@@ skipping 54 matching lines @@
       "session_types_unittest.cc",
     ]
     deps = [
       ":sessions",
       "//base/test:test_support",
       "//testing/gtest",
       "//third_party/protobuf:protobuf_lite",
     ]
   }
 }