Add a Mojo EDK for Chrome that uses one OS pipe per message pipe.

components/mus/public/cpp/tests/BUILD.gn

 # Copyright 2014 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("//build/config/ui.gni")
 import("//testing/test.gni")
 
 source_set("test_support") {
   testonly = true
 
@@ skipping 20 matching lines @@
     "view_unittest.cc",
   ]
 
   deps = [
     "//base",
     "//base/test:test_support",
     "//components/mus/public/cpp",
     "//mojo/application/public/cpp",
     "//testing/gtest",
     "//third_party/mojo/src/mojo/public/cpp/system",
-    "//third_party/mojo/src/mojo/edk/system",
     "//ui/mojo/geometry:interfaces",
   ]
 
+  if (use_chrome_edk) {
+    deps += [ "//mojo/edk/system" ]
+  } else {
+    deps += [ "//third_party/mojo/src/mojo/edk/system" ]
+  }
+
   if (use_x11) {
     deps += [ "//ui/gfx/x" ]
   }
 }