Decompose //extensions/browser/BUILD.gn

extensions/browser/mojo/BUILD.gn

Index: extensions/browser/mojo/BUILD.gn
diff --git a/extensions/browser/mojo/BUILD.gn b/extensions/browser/mojo/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..43eb068adab803155e9149e35e86b02646dc9100
--- /dev/null
+++ b/extensions/browser/mojo/BUILD.gn
@@ -0,0 +1,18 @@
+# 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.
+
+source_set("mojo") {
+  sources = [
+    "keep_alive_impl.cc",
+    "keep_alive_impl.h",
+    "service_registration.cc",
+    "service_registration.h",
+    "stash_backend.cc",
+    "stash_backend.h",
+  ]
+
+  deps = [
+    "//extensions/common:mojo",
+  ]
+}