Build public cast_shell on x86 with GN.

chromecast/renderer/media/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.
+
+source_set("media") {
+  sources = [
+    "audio_pipeline_proxy.cc",
+    "audio_pipeline_proxy.h",
+    "chromecast_media_renderer_factory.cc",
+    "chromecast_media_renderer_factory.h",
+    "cma_message_filter_proxy.cc",
+    "cma_message_filter_proxy.h",
+    "media_channel_proxy.cc",
+    "media_channel_proxy.h",
+    "media_pipeline_proxy.cc",
+    "media_pipeline_proxy.h",
+    "video_pipeline_proxy.cc",
+    "video_pipeline_proxy.h",
+  ]
+
+  deps = [
+    "//base",
+    "//chromecast/common/media",
+    "//chromecast/media",
+    "//content/public/renderer",
+    "//ipc",
+    "//media",
+  ]
+}