Make //blimp/client/app a real embedder of //blimp/client/public

blimp/client/core/render_widget/BUILD.gn

 # 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("render_widget") {
   visibility = [
-    "//blimp/client/app:session",  # TODO(nyquist): Remove this. See crbug/651964.
     "//blimp/client/core/*",
+    "//blimp/engine:browser_tests",
   ]
 
   sources = [
     "blimp_document.cc",
     "blimp_document.h",
     "blimp_document_manager.cc",
     "blimp_document_manager.h",
     "render_widget_feature.cc",
     "render_widget_feature.h",
   ]
@@ skipping 57 matching lines @@
     "//blimp/client/test/compositor",
     "//blimp/common",
     "//blimp/net:test_support",
     "//cc/proto",
     "//cc/surfaces",
     "//net",
     "//net:test_support",
     "//testing/gtest",
   ]
 }