Add chrome://vr-shell-ui internal page

chrome/browser/ui/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/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/split_static_library.gni")
 import("//chrome/common/features.gni")
 import("//media/media_options.gni")
@@ skipping 2160 matching lines @@
         "webui/offline/offline_internals_ui_message_handler.h",
         "webui/popular_sites_internals_message_handler.cc",
         "webui/popular_sites_internals_message_handler.h",
         "webui/popular_sites_internals_ui.cc",
         "webui/popular_sites_internals_ui.h",
         "webui/snippets_internals_message_handler.cc",
         "webui/snippets_internals_message_handler.h",
         "webui/snippets_internals_ui.cc",
         "webui/snippets_internals_ui.h",
       ]
+      if (enable_vr_shell) {
+        defines += [ "ENABLE_VR_SHELL" ]
+        sources += [
+          "webui/vr_shell/vr_shell_ui_message_handler.cc",
+          "webui/vr_shell/vr_shell_ui_message_handler.h",
+          "webui/vr_shell/vr_shell_ui_ui.cc",
+          "webui/vr_shell/vr_shell_ui_ui.h",
+        ]
+      }
+      if (enable_vr_shell_ui_dev) {
+        assert(enable_vr_shell)
+        defines += [ "ENABLE_VR_SHELL_UI_DEV" ]

[sky, 2016/09/16 22:57:31]

Why do we need to ifdefs and features? Isn't eanble_vr_shell enough?

[bshe, 2016/09/16 23:28:04]

enable_vr_shell_ui_dev controls a feature which implemented in 
chrome/browser/ui/webui/vr_shell/vr_shell_ui_ui.cc That file is compiled
when enable_vr_shell is set. So ifdef is needed to conditionally compile some
of the code. enable_vr_shell_ui_dev is a sub flag of enable_vr_shell in a sense.
I can probably divide vr_shell_ui_ui.cc to two files to remove the need for
ifdef if you prefer.

+      }
       deps += [
         "//chrome/browser:jni_headers",
         "//components/web_contents_delegate_android",
       ]
       deps -= [ "//ui/events" ]
     }
   } else {
     sources += [ "browser_window.h" ]
   }
 
@@ skipping 1175 matching lines @@
       "passwords/passwords_model_delegate_mock.cc",
       "passwords/passwords_model_delegate_mock.h",
     ]
     deps += [ "//chrome/test:test_support_ui" ]
   }
 
   if (enable_extensions) {
     deps += [ "//extensions/browser" ]
   }
 }