Remove enable_webvr from build/config, and move it to the buildflag_header system.

chrome/browser/android/chrome_jni_registrar.cc

Index: chrome/browser/android/chrome_jni_registrar.cc
diff --git a/chrome/browser/android/chrome_jni_registrar.cc b/chrome/browser/android/chrome_jni_registrar.cc
index bc699aab062829349e8df6f9a0eb50c7a8ae794a..0b83b6043f7891030faed439a0253fad1a62128f 100644
--- a/chrome/browser/android/chrome_jni_registrar.cc
+++ b/chrome/browser/android/chrome_jni_registrar.cc
@@ -182,13 +182,14 @@
 #include "components/url_formatter/android/component_jni_registrar.h"
 #include "components/variations/android/component_jni_registrar.h"
 #include "components/web_contents_delegate_android/component_jni_registrar.h"
+#include "device/vr/features.h"
 #include "printing/features/features.h"
 
 #if BUILDFLAG(ENABLE_PRINTING) && !BUILDFLAG(ENABLE_PRINT_PREVIEW)
 #include "printing/printing_context_android.h"
 #endif
 
-#if defined(ENABLE_WEBVR)
+#if BUILDFLAG(ENABLE_WEBVR)
 #include "chrome/browser/android/vr_shell/vr_shell.h"
 #include "chrome/browser/android/vr_shell/vr_shell_delegate.h"
 #include "third_party/gvr-android-sdk/display_synchronizer_jni.h"
@@ -414,7 +415,7 @@ static base::android::RegistrationMethod kChromeRegisteredMethods[] = {
     {"UsbChooserDialogAndroid", UsbChooserDialogAndroid::Register},
     {"Variations", variations::android::RegisterVariations},
     {"VariationsSession", chrome::android::RegisterVariationsSession},
-#if defined(ENABLE_WEBVR)
+#if BUILDFLAG(ENABLE_WEBVR)
     {"VrShell", vr_shell::RegisterVrShell},
     {"VrShellDelegate", vr_shell::RegisterVrShellDelegate},
     {"DisplaySynchronizer",