[NoStatePrefetch] Do not send responses to renderer in prefetch mode.

content/browser/loader/resource_dispatcher_host_impl.cc

Index: content/browser/loader/resource_dispatcher_host_impl.cc
diff --git a/content/browser/loader/resource_dispatcher_host_impl.cc b/content/browser/loader/resource_dispatcher_host_impl.cc
index 847f0fd5f9d82e6dd5d54a4e4db3d75360c35fde..32d18ef8250622c129fe8fb58b8917f7318255a3 100644
--- a/content/browser/loader/resource_dispatcher_host_impl.cc
+++ b/content/browser/loader/resource_dispatcher_host_impl.cc
@@ -1638,12 +1638,16 @@ ResourceDispatcherHostImpl::CreateResourceHandler(
     }
   }
 
+  const bool detached =

[mmenke, 2016/08/22 14:08:23]

style:  const is generally not used for stack variables that aren't compile-time
constants.

+      delegate()->ShouldSinkResponse(request, request_data.resource_type);

[mmenke, 2016/08/22 14:08:23]

sink / detach:  Should use consistent naming.

+
   // Prefetches and <a ping> requests outlive their child process.
-  if (!sync_result && IsDetachableResourceType(request_data.resource_type)) {
+  if (detached ||
+      (!sync_result && IsDetachableResourceType(request_data.resource_type))) {

[mmenke, 2016/08/22 14:08:22]

Should we instead introduce a resource type for this instead?

[mmenke, 2016/08/22 14:08:23]

BUG:  The sync_result check should cover the case detached is true - we don't
want to let the embedder cause the entire renderer to hang, no matter how much
it may want to.

[mmenke, 2016/08/22 14:11:00]

Moreover, do we really want the embedder controlling behavior here?  The new
magic prerender type has logic in content/, so I assume content or blink knows
that this is a not a real navigation, and the renderer doesn't really need the
data.  So it doesn't seem like the embedder should be controlling this.

     handler.reset(new DetachableResourceHandler(
         request,
         base::TimeDelta::FromMilliseconds(kDefaultDetachableCancelDelayMs),
-        std::move(handler)));
+        detached ? nullptr : std::move(handler)));
   }
 
   // PlzNavigate: If using --enable-browser-side-navigation, the