Don't record end mark of traces for loading resource too early

Before this CL, we called ResourceLoadContinuesBeyondScope()
only after StartLoad() succeeded. This wasn't enough to cover
all loading cases and ResourceLoader::DidFinishLoading()
could be called when we already record END marks for tracing.

This CL changes to call ResourceLoadContinuesBeyondScope()
when resource still needs loading or is loading.

Bug: 900815
Change-Id: I478e1e36c41b0fdc50f43c7d99687ea615eaaf2a
Reviewed-on: https://chromium-review.googlesource.com/c/1312174Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Commit-Queue: Kenichi Ishibashi <bashi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604543}

third_party/blink/renderer/platform/loader/fetch/resource_fetcher.cc

@@ -917,9 +917,7 @@ Resource* ResourceFetcher::RequestResource(
   // the resource was already initialized for the revalidation here, but won't
   // start loading.
   if (ResourceNeedsLoad(resource, params, policy)) {
-    if (StartLoad(resource)) {
-      scoped_resource_load_tracker.ResourceLoadContinuesBeyondScope();
-    } else {
+    if (!StartLoad(resource)) {
       resource->FinishAsError(ResourceError::CancelledError(params.Url()),
                               Context().GetLoadingTaskRunner().get());
     }
@@ -928,6 +926,11 @@ Resource* ResourceFetcher::RequestResource(
   if (policy != kUse)
     InsertAsPreloadIfNecessary(resource, params, resource_type);
 
+  if (resource->Identifier() == identifier &&
+      (resource->StillNeedsLoad() || resource->IsLoading())) {
+    scoped_resource_load_tracker.ResourceLoadContinuesBeyondScope();
+  }
+
   return resource;
 }