Move BroadcastChannel browser code from components/ to content/browser.

components/webmessaging/public/interfaces/BUILD.gn

Index: components/webmessaging/public/interfaces/BUILD.gn
diff --git a/components/webmessaging/public/interfaces/BUILD.gn b/components/webmessaging/public/interfaces/BUILD.gn
deleted file mode 100644
index f1c37e12fe800752fd1d526e9af7a2adc4ff4ff7..0000000000000000000000000000000000000000
--- a/components/webmessaging/public/interfaces/BUILD.gn
+++ /dev/null
@@ -1,16 +0,0 @@
-# Copyright 2016 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("//mojo/public/tools/bindings/mojom.gni")
-
-mojom("interfaces") {
-  sources = [
-    "broadcast_channel.mojom",
-  ]
-  deps = [
-    "//url/mojo:url_mojom_origin",
-  ]
-
-  use_new_wrapper_types = false
-}