Introduce Origin-Trial for Service Worker Navigation Preload

content/browser/service_worker/service_worker_dispatcher_host.cc

Index: content/browser/service_worker/service_worker_dispatcher_host.cc
diff --git a/content/browser/service_worker/service_worker_dispatcher_host.cc b/content/browser/service_worker/service_worker_dispatcher_host.cc
index c0e32cee57284480dc9383c33efd166ab64c10c8..cd36e3ee85c0c5925ef07d8a2b2fd5d5865712a6 100644
--- a/content/browser/service_worker/service_worker_dispatcher_host.cc
+++ b/content/browser/service_worker/service_worker_dispatcher_host.cc
@@ -81,6 +81,26 @@ WebContents* GetWebContents(int render_process_id, int render_frame_id) {
   return WebContents::FromRenderFrameHost(rfh);
 }
 
+std::string GetNavigationPreloadDisabledErrorMessage(
+    ServiceWorkerVersion::NavigationPreloadSupportStatus support_status) {
+  switch (support_status) {
+    case ServiceWorkerVersion::NavigationPreloadSupportStatus::SUPPORTED:
+      NOTREACHED();
+      break;
+    case ServiceWorkerVersion::NavigationPreloadSupportStatus::
+        NOT_SUPPORTED_FILELD_TRIAL_STOPPED:
+      return "Navigation Preload field trial is stopped.";

[falken, 2017/01/13 09:13:20]

nit: is "field trial" a term we use in public? Maybe "The Navigation Preload
origin trial has ended."

[horo, 2017/01/13 09:27:57]

Done.

+    case ServiceWorkerVersion::NavigationPreloadSupportStatus::
+        NOT_SUPPORTED_DISABLED_BY_COMMAND_LINE:
+      return "Navigation Preload is disabled by command line flag.";
+    case ServiceWorkerVersion::NavigationPreloadSupportStatus::
+        NOT_SUPPORTED_NO_VALID_ORIGIN_TRIAL_TOKEN:
+      return "No valid Navigation Preload Orignin Trial token for the script.";

[falken, 2017/01/13 09:13:20]

nit: "Origin"

May be good to say "service worker script" or even dynamically add the script
URL. If I understand correctly, if you do this from a document:

navigator.serviceWorker.register('sw.js').then(reg =>
reg.navigationPreload.enable());

you'd see "No valid Navigation Preload Orignin Trial token for the script" which
could be confusing.

My preferred error message would be something like "The service worker script
does not have a valid Navigation Preload Origin Trial token." 

[horo, 2017/01/13 09:27:57]

Done.

+  }
+  NOTREACHED();
+  return "";
+}
+
 }  // namespace
 
 ServiceWorkerDispatcherHost::ServiceWorkerDispatcherHost(
@@ -717,6 +737,17 @@ void ServiceWorkerDispatcherHost::OnEnableNavigationPreload(
     return;
   }
 
+  ServiceWorkerVersion::NavigationPreloadSupportStatus support_status =
+      registration->active_version()->GetNavigationPreloadSupportStatus();
+  if (support_status !=
+      ServiceWorkerVersion::NavigationPreloadSupportStatus::SUPPORTED) {
+    Send(new ServiceWorkerMsg_EnableNavigationPreloadError(
+        thread_id, request_id, WebServiceWorkerError::ErrorTypeAbort,
+        std::string(kEnableNavigationPreloadErrorPrefix) +
+            GetNavigationPreloadDisabledErrorMessage(support_status)));
+    return;
+  }
+
   std::vector<GURL> urls = {provider_host->document_url(),
                             registration->pattern()};
   if (!ServiceWorkerUtils::AllOriginsMatchAndCanAccessServiceWorkers(urls)) {
@@ -859,6 +890,16 @@ void ServiceWorkerDispatcherHost::OnSetNavigationPreloadHeader(
     return;
   }
 
+  ServiceWorkerVersion::NavigationPreloadSupportStatus support_status =
+      registration->active_version()->GetNavigationPreloadSupportStatus();
+  if (support_status !=
+      ServiceWorkerVersion::NavigationPreloadSupportStatus::SUPPORTED) {
+    Send(new ServiceWorkerMsg_SetNavigationPreloadHeaderError(
+        thread_id, request_id, WebServiceWorkerError::ErrorTypeAbort,
+        std::string(kSetNavigationPreloadHeaderErrorPrefix) +
+            GetNavigationPreloadDisabledErrorMessage(support_status)));
+    return;
+  }
   std::vector<GURL> urls = {provider_host->document_url(),
                             registration->pattern()};
   if (!ServiceWorkerUtils::AllOriginsMatchAndCanAccessServiceWorkers(urls)) {