Refactor ChooserBubbleUiViewDelegate

components/chooser_controller/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("chooser_controller") {
   sources = [
     "chooser_controller.cc",
     "chooser_controller.h",
   ]
 
   deps = [
     "//base",
     "//content/public/browser",
   ]
 }
+
+source_set("test_support") {
+  testonly = true
+
+  sources = [
+    "mock_chooser_controller.cc",
+    "mock_chooser_controller.h",
+  ]
+
+  deps = [
+    ":chooser_controller",
+    "//base",
+  ]
+
+  public_deps = [
+    "//testing/gmock",
+  ]
+}