[cast_channel] Make cast_channel related files not depend on "cast_channel.h"

extensions/browser/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.
 
 import("//build/config/features.gni")
 import("//extensions/features/features.gni")
 
 group("browser") {
   public_deps = [
     "//extensions/browser:browser_context_keyed_service_factories",
@@ skipping 27 matching lines @@
 }
 
 source_set("browser_sources") {
   visibility = [ "./*" ]
 
   sources = []
 
   deps = [
     "//base:i18n",
     "//components/cast_certificate",
+    "//components/cast_channel",
     "//components/guest_view/browser",
     "//components/keyed_service/content",
     "//components/keyed_service/core",
     "//components/pref_registry",
     "//components/sessions",
     "//components/update_client",
     "//components/version_info",
     "//components/web_cache/browser",
     "//components/web_modal",
     "//components/zoom",
@@ skipping 452 matching lines @@
 
   if (is_chromeos) {
     sources += [
       "api/audio/audio_device_id_calculator_unittest.cc",
       "api/webcam_private/visca_webcam_unittest.cc",
     ]
 
     deps += [ "//chromeos:test_support" ]
   }
 }