Decoupling rtc_base from apple specific code [without cyclic deps]

webrtc/modules/video_capture/BUILD.gn

 # Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import("../../webrtc.gni")
 
@@ skipping 171 matching lines @@
         "../../test:video_test_common",
         "../utility",
         "//testing/gtest",
       ]
       deps += [ "../../test:test_main" ]
 
       if (!build_with_chromium && is_clang) {
         # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
         suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
       }
+      if (is_ios) {
+        deps += [ "../../rtc_base:rtc_base_apple" ]
+      }
     }
   }
 }