Add the ability to disable the global CSP in a controller

e.g:

    class LegacyPagesController < ApplicationController
      content_security_policy false, only: :index
    end

actionpack/lib/action_controller/metal/content_security_policy.rb

@@ -14,13 +14,17 @@ module ActionController #:nodoc:
     end
 
     module ClassMethods
-      def content_security_policy(**options, &block)
+      def content_security_policy(enabled = true, **options, &block)
         before_action(options) do
           if block_given?
             policy = request.content_security_policy.clone
             yield policy
             request.content_security_policy = policy
           end
+
+          unless enabled
+            request.content_security_policy = nil
+          end
         end
       end
 

actionpack/test/dispatch/content_security_policy_test.rb

@@ -258,6 +258,8 @@ class ContentSecurityPolicyIntegrationTest < ActionDispatch::IntegrationTest
       p.script_src :self
     end
 
+    content_security_policy(false, only: :no_policy)
+
     content_security_policy_report_only only: :report_only
 
     def index
@@ -280,6 +282,10 @@ class ContentSecurityPolicyIntegrationTest < ActionDispatch::IntegrationTest
       head :ok
     end
 
+    def no_policy
+      head :ok
+    end
+
     private
       def condition?
         params[:condition] == "true"
@@ -294,6 +300,7 @@ class ContentSecurityPolicyIntegrationTest < ActionDispatch::IntegrationTest
       get "/conditional", to: "policy#conditional"
       get "/report-only", to: "policy#report_only"
       get "/script-src", to: "policy#script_src"
+      get "/no-policy", to: "policy#no_policy"
     end
   end
 
@@ -353,6 +360,13 @@ class ContentSecurityPolicyIntegrationTest < ActionDispatch::IntegrationTest
     assert_policy "script-src 'self' 'nonce-iyhD0Yc0W+c='"
   end
 
+  def test_generates_no_content_security_policy
+    get "/no-policy"
+
+    assert_nil response.headers["Content-Security-Policy"]
+    assert_nil response.headers["Content-Security-Policy-Report-Only"]
+  end
+
   private
 
     def env_config