Enable the mojo-based serial API in the renderer behind a flag.

extensions/browser/service_registration_manager.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "extensions/browser/service_registration_manager.h"
 
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/render_frame_host.h"
@@ skipping 27 matching lines @@
   }
 }
 
 ServiceRegistrationManager::~ServiceRegistrationManager() {
 }
 
 ServiceRegistrationManager* ServiceRegistrationManager::GetSharedInstance() {
   return g_lazy_instance.Pointer();
 }
 
+void ServiceRegistrationManager::ClearOverridesForTest() {
+  test_factories_.clear();
+}
+
 void ServiceRegistrationManager::AddToRenderFrame(
     content::RenderFrameHost* render_frame_host) {
   content::BrowserContext* context =
       render_frame_host->GetProcess()->GetBrowserContext();
   content::SiteInstance* site_instance = render_frame_host->GetSiteInstance();
   GURL site_url = site_instance->GetSiteURL();
   ExtensionRegistry* registry = ExtensionRegistry::Get(context);
 
   // TODO(sammc): Handle content scripts and web pages that have access to some
   // extension APIs.
@@ skipping 10 matching lines @@
           extension, render_frame_host->GetProcess()->GetID());
   for (const auto& factory : factories_) {
     // Note: The RenderFrame has not yet navigated to a particular URL so we
     // pass |site_url| as the URL for permission checking. This is sufficient
     // for now because we only reach this point for URLs with a scheme of
     // chrome-extension. This will need to change once we begin supporting
     // arbitrary sites URLs that may have access to extensions APIs.
     if (ExtensionAPI::GetSharedInstance()
             ->IsAvailable(factory.first, extension, context_type, site_url)
             .is_available()) {
-      factory.second->Register(render_frame_host->GetServiceRegistry());
+      auto test_factory = test_factories_.find(factory.second->GetName());
+      if (test_factory != test_factories_.end()) {
+        test_factory->second->Register(render_frame_host->GetServiceRegistry());
+      } else {
+        factory.second->Register(render_frame_host->GetServiceRegistry());
+      }
     }
   }
 }
 
 }  // namespace extensions