service worker: Plumb NavigationPreloadManager.enable/disable to browser-side

content/common/service_worker/service_worker_messages.h

Index: content/common/service_worker/service_worker_messages.h
diff --git a/content/common/service_worker/service_worker_messages.h b/content/common/service_worker/service_worker_messages.h
index 696bac747aa3fe707440a5051328ed37385994bd..b3df9acc20eb291bbc1e4c974f09fc8d6d354ee0 100644
--- a/content/common/service_worker/service_worker_messages.h
+++ b/content/common/service_worker/service_worker_messages.h
@@ -187,6 +187,14 @@ IPC_MESSAGE_CONTROL3(ServiceWorkerHostMsg_GetRegistrationForReady,
                      int /* request_id */,
                      int /* provider_id */)
 
+// Asks the browser to enable/disable navigation preload for a registration.
+IPC_MESSAGE_CONTROL5(ServiceWorkerHostMsg_EnableNavigationPreload,
+                     int /* thread_id */,
+                     int /* request_id */,
+                     int /* provider_id */,
+                     int64_t /* registration_id */,
+                     bool /* enable */)
+
 // Sends ExtendableMessageEvent to a service worker (renderer->browser).
 IPC_MESSAGE_CONTROL5(
     ServiceWorkerHostMsg_PostMessageToWorker,
@@ -475,6 +483,15 @@ IPC_MESSAGE_CONTROL4(ServiceWorkerMsg_SetControllerServiceWorker,
                      content::ServiceWorkerObjectInfo,
                      bool /* should_notify_controllerchange */)
 
+IPC_MESSAGE_CONTROL2(ServiceWorkerMsg_DidEnableNavigationPreload,
+                     int /* thread_id */,
+                     int /* request_id */)
+IPC_MESSAGE_CONTROL4(ServiceWorkerMsg_EnableNavigationPreloadError,
+                     int /* thread_id */,
+                     int /* request_id */,
+                     blink::WebServiceWorkerError::ErrorType /* code */,
+                     base::string16 /* message */)

[nasko, 2016/10/21 16:42:02]

Can we transfer the message as std::string and do the conversion in the renderer
process? It will save us memory, as most strings are going to be ASCII anyway
and converting to string16 will double the size.

[falken, 2016/10/24 05:14:42]

Yes this puzzled me recently too. For some reason all service worker messages
use string16. It might be required to support weird strings with unpaired
surrogates (see https://bugs.chromium.org/p/chromium/issues/detail?id=592011 and
https://codereview.chromium.org/1768063002/) but we shouldn't worry about
supporting those. If WebString::fromUtf8 results in a null string,
ServiceWorkerError::take will use the default message anyway without crashing.

Done for this patch, I'll update the other messages too if this makes sense.

[nasko, 2016/10/24 15:54:48]

Thanks for the background info!
 
Yes, it makes sense. The less data we shuffle through process boundaries, the
more performant we will be and less memory usage. I'll be happy to review those
patches :).

+
 // Sends MessageEvent to a client document (browser->renderer).
 IPC_MESSAGE_CONTROL1(ServiceWorkerMsg_MessageToDocument,
                      ServiceWorkerMsg_MessageToDocument_Params)