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

chrome/browser/ui/BUILD.gn

Index: chrome/browser/ui/BUILD.gn
diff --git a/chrome/browser/ui/BUILD.gn b/chrome/browser/ui/BUILD.gn
index 2ad86143e7a0d0863dffb30cf2d7e40f2ce1bc08..aa089007506547635b327123f80f0a7a038c91fc 100644
--- a/chrome/browser/ui/BUILD.gn
+++ b/chrome/browser/ui/BUILD.gn
@@ -2178,6 +2178,19 @@ split_static_library("ui") {
         "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",