Fix custom scheme not registered as service worker scheme

shell/app/electron_content_client.cc

@@ -187,13 +187,9 @@ void ElectronContentClient::AddAdditionalSchemes(Schemes* schemes) {
   auto* command_line = base::CommandLine::ForCurrentProcess();
   std::string process_type =
       command_line->GetSwitchValueASCII(::switches::kProcessType);
-  // Browser Process registration happens in
-  // `api::Protocol::RegisterSchemesAsPrivileged`
-  //
-  // Renderer Process registration happens in `RendererClientBase`
-  //
-  // We use this for registration to network utility process
-  if (process_type == ::switches::kUtilityProcess) {
+  // Register schemes for browser process and network utility process, the
+  // registration for renderer process happens in `RendererClientBase`.
+  if (process_type.empty() || process_type == ::switches::kUtilityProcess) {
     AppendDelimitedSwitchToVector(switches::kServiceWorkerSchemes,
                                   &schemes->service_worker_schemes);
     AppendDelimitedSwitchToVector(switches::kStandardSchemes,

shell/browser/api/electron_api_protocol.cc

@@ -10,6 +10,7 @@
 
 #include "base/command_line.h"
 #include "base/stl_util.h"
+#include "content/common/url_schemes.h"
 #include "content/public/browser/child_process_security_policy.h"
 #include "gin/object_template_builder.h"
 #include "shell/browser/browser.h"
@@ -149,6 +150,14 @@ void RegisterSchemesAsPrivileged(gin_helper::ErrorThrower thrower,
                          g_standard_schemes);
   AppendSchemesToCmdLine(electron::switches::kStreamingSchemes,
                          g_streaming_schemes);
+
+  // The scheme registration happens before user's main script is executed, so
+  // we have to explicitly do a re-registration to make the new scheme
+  // effective.
+  // Note that while the API is marked as ForTests, it is safe to call in this
+  // use case, and it has DCHECK to ensure we are not making changes to schemes
+  // _after_ any code has read the scheme registry.
+  content::ReRegisterContentSchemesForTests();
 }
 
 namespace {