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

components/webmessaging/BUILD.gn

Index: components/webmessaging/BUILD.gn
diff --git a/components/webmessaging/BUILD.gn b/components/webmessaging/BUILD.gn
deleted file mode 100644
index dc816734c7f2dfdf50ae3289ca088a51f0ca8ea3..0000000000000000000000000000000000000000
--- a/components/webmessaging/BUILD.gn
+++ /dev/null
@@ -1,17 +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.
-
-static_library("webmessaging") {
-  sources = [
-    "broadcast_channel_provider.cc",
-    "broadcast_channel_provider.h",
-  ]
-
-  deps = [
-    "//base",
-    "//components/webmessaging/public/interfaces",
-    "//mojo/common",
-    "//url",
-  ]
-}