From c12adfd55a80d6c48a426f876a48a069649418be Mon Sep 17 00:00:00 2001
From: Shelley Vohr <shelley.vohr@gmail.com>
Date: Tue, 21 Jan 2020 19:14:04 -0800
Subject: [PATCH] fix: some websites using WebComponents V0 not loading

---
 buildflags/BUILD.gn           | 1 +
 buildflags/buildflags.gni     | 2 ++
 shell/browser/feature_list.cc | 6 ++++++
 3 files changed, 9 insertions(+)

diff --git a/buildflags/BUILD.gn b/buildflags/BUILD.gn
index 8a93310cff1cf..69492dfd6781d 100644
--- a/buildflags/BUILD.gn
+++ b/buildflags/BUILD.gn
@@ -21,6 +21,7 @@ buildflag_header("buildflags") {
     "ENABLE_ELECTRON_EXTENSIONS=$enable_electron_extensions",
     "ENABLE_BUILTIN_SPELLCHECKER=$enable_builtin_spellchecker",
     "ENABLE_PICTURE_IN_PICTURE=$enable_picture_in_picture",
+    "ENABLE_WEBCOMPONENTS_V0=$enable_webcomponents_v0",
     "ENABLE_MEDIA_KEY_OVERRIDES=$enable_media_key_overrides",
     "OVERRIDE_LOCATION_PROVIDER=$enable_fake_location_provider",
   ]
diff --git a/buildflags/buildflags.gni b/buildflags/buildflags.gni
index c5f9edd107cb7..27738410c611e 100644
--- a/buildflags/buildflags.gni
+++ b/buildflags/buildflags.gni
@@ -22,6 +22,8 @@ declare_args() {
 
   enable_picture_in_picture = true
 
+  enable_webcomponents_v0 = true
+
   enable_media_key_overrides = true
 
   # Provide a fake location provider for mocking
diff --git a/shell/browser/feature_list.cc b/shell/browser/feature_list.cc
index b19596b7b429b..8e12627a7d94f 100644
--- a/shell/browser/feature_list.cc
+++ b/shell/browser/feature_list.cc
@@ -27,6 +27,12 @@ void InitializeFeatureList() {
   // when node integration is enabled.
   disable_features +=
       std::string(",") + features::kSpareRendererForSitePerProcess.name;
+#if BUILDFLAG(ENABLE_WEBCOMPONENTS_V0)
+  // https://www.polymer-project.org/blog/2018-10-02-webcomponents-v0-deprecations
+  // Any website which uses older WebComponents will currently fail in Electron.
+  enable_features += std::string(",") + "WebComponentsV0Enabled";
+#endif
+
 #if !BUILDFLAG(ENABLE_PICTURE_IN_PICTURE)
   disable_features += std::string(",") + media::kPictureInPicture.name;
 #endif