Remove ENABLE_VR_SHELL compile-time define.

chrome/browser/android/vr_shell/vr_shell.cc

Index: chrome/browser/android/vr_shell/vr_shell.cc
diff --git a/chrome/browser/android/vr_shell/vr_shell.cc b/chrome/browser/android/vr_shell/vr_shell.cc
index e1d651507a47dbd1f60e62474e5b3e9257b006a5..32345ad27caa3c5c6b52548d0f1b7ece1d4dd04a 100644
--- a/chrome/browser/android/vr_shell/vr_shell.cc
+++ b/chrome/browser/android/vr_shell/vr_shell.cc
@@ -31,6 +31,7 @@
 #include "content/public/browser/render_widget_host.h"
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
+#include "content/public/common/content_features.h"
 #include "content/public/common/referrer.h"
 #include "device/vr/android/gvr/gvr_device.h"
 #include "device/vr/android/gvr/gvr_device_provider.h"
@@ -72,6 +73,7 @@ VrShell::VrShell(JNIEnv* env,
                  gvr_context* gvr_api,
                  bool reprojected_rendering)
     : WebContentsObserver(ui_contents),
+      feature_enabled_(base::FeatureList::IsEnabled(features::kVrShell)),

[amp, 2017/02/07 19:26:01]

I think the preference is to check the feature directly where it is used, rather
than save the value like this, but I'll defer to someone more familiar with
feature flags to say for sure.

[cjgrant, 2017/02/07 20:10:17]

Why would we want to incur this extra overhead on every button-press?  But more
importantly, we initialize VR components based on the feature... I think
allowing behavior to change after the fact would be dangerous.

[amp, 2017/02/07 20:23:10]

I'm not familiar with the overhead differences in c++ of having it saved as a
local property versus pulling it statically.  I kind of thought they would be
pretty similar (but I don't really have anything to base that assumption on).

       main_contents_(main_contents),
       content_compositor_(
           base::MakeUnique<VrCompositor>(content_window, false)),
@@ -334,9 +336,8 @@ void VrShell::GvrDelegateReady() {
 }
 
 void VrShell::AppButtonPressed() {
-#if defined(ENABLE_VR_SHELL)
-  html_interface_->HandleAppButtonClicked();
-#endif
+  if (feature_enabled_)

[amp, 2017/02/07 20:23:10]

Isn't this going to be supported in WebVR for menu mode soon anyways?  (or am I
confusing what the app button does).

[cjgrant, 2017/02/07 20:28:25]

You're right.  Once the app button works properly in WebVR, and menu mode is
tested in WebVR, this check will disappear.

+    html_interface_->HandleAppButtonClicked();
 }
 
 void VrShell::ContentPhysicalBoundsChanged(JNIEnv* env,
@@ -407,6 +408,7 @@ void VrShell::DoUiAction(const UiAction action,
       SetContentPaused(paused);
       break;
     }
+

[cjgrant, 2017/02/07 20:10:17]

I'll remove this line.

[cjgrant, 2017/02/07 22:16:54]

Done.

 #if defined(ENABLE_VR_SHELL_UI_DEV)
     case RELOAD_UI:
       ui_contents_->GetController().Reload(content::ReloadType::NORMAL, false);