Keep `CHROME_HEADLESS` working while displaying a deprecation warning

qa/qa/runtime/env.rb

 # frozen_string_literal: true
 
+require 'active_support/deprecation'
 require 'gitlab/qa'
 require 'uri'
 
@@ -66,7 +67,11 @@ module QA
 
       # set to 'false' to have the browser run visibly instead of headless
       def webdriver_headless?
-        enabled?(ENV['WEBDRIVER_HEADLESS'])
+        if ENV.key?('CHROME_HEADLESS')
+          ActiveSupport::Deprecation.warn("CHROME_HEADLESS is deprecated. Use WEBDRIVER_HEADLESS instead.")
+        end
+
+        enabled?(ENV['WEBDRIVER_HEADLESS']) || enabled?(ENV['CHROME_HEADLESS'])
       end
 
       # set to 'true' to have Chrome use a fixed profile directory

qa/spec/runtime/env_spec.rb

@@ -55,6 +55,11 @@ RSpec.describe QA::Runtime::Env do
   end
 
   describe '.webdriver_headless?' do
+    before do
+      # We need to set this because we have a fallback for CHROME_HEADLESS
+      stub_env('CHROME_HEADLESS', 'false')
+    end
+
     it_behaves_like 'boolean method',
       method: :webdriver_headless?,
       env_key: 'WEBDRIVER_HEADLESS',

spec/support/capybara.rb

@@ -61,7 +61,7 @@ Capybara.register_driver :chrome do |app|
   options.add_argument("no-sandbox")
 
   # Run headless by default unless WEBDRIVER_HEADLESS specified
-  options.add_argument("headless") unless ENV['WEBDRIVER_HEADLESS'] =~ /^(false|no|0)$/i
+  options.add_argument("headless") unless ENV['WEBDRIVER_HEADLESS'] =~ /^(false|no|0)$/i || ENV['CHROME_HEADLESS'] =~ /^(false|no|0)$/i
 
   # Disable /dev/shm use in CI. See https://gitlab.com/gitlab-org/gitlab/issues/4252
   options.add_argument("disable-dev-shm-usage") if ENV['CI'] || ENV['CI_SERVER']

spec/support/helpers/live_debugger.rb

@@ -24,6 +24,8 @@ module LiveDebugger
   end
 
   def is_headless_disabled?
-    ENV['WEBDRIVER_HEADLESS'] =~ /^(false|no|0)$/i
+    ActiveSupport::Deprecation.warn("CHROME_HEADLESS is deprecated. Use WEBDRIVER_HEADLESS instead.") if ENV.key?('CHROME_HEADLESS')
+
+    ENV['WEBDRIVER_HEADLESS'] =~ /^(false|no|0)$/i || ENV['CHROME_HEADLESS'] =~ /^(false|no|0)$/i
   end
 end