Remove PlatformClientAuth interface from upstream.

chromecast/common/BUILD.gn

 # Copyright 2015 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("//chromecast/chromecast.gni")
-
 source_set("common") {
   sources = [
     "cast_content_client.cc",
     "cast_content_client.h",
     "cast_resource_delegate.cc",
     "cast_resource_delegate.h",
     "global_descriptors.h",
   ]
 
   deps = [
     "//base",
     "//chromecast/base",
     "//chromecast/base:cast_version",
     "//chromecast/common/media",
     "//content/public/common",
     "//ui/base",
     "//ui/gfx",
     "//url:url",
   ]
-
-  public_deps = [
-    ":platform_client_auth",
-  ]
 }
-
-# target for definition and a simple implementation of PlatformClientAuth
-# b/30398176 components that depend on PlatformClientAuth should directly
-# depend on this target instead of //chromecast/common/
-source_set("platform_client_auth") {
-  sources = [
-    "platform_client_auth.h",
-  ]
-
-  if (chromecast_branding == "public") {
-    sources += [ "platform_client_auth_simple.cc" ]
-  }
-}