Log file resource dependencies for ClusterFuzz.

ClusterFuzz relied on NetworkDelegate::NotifyBeforeURLRequest to
know a test case's resource dependencies and archive them. This
regressed when file url loads were moved to FileURLLoader. Add
logging to capture them for file loads.

Bug: 715656
Change-Id: Ibb2938a569223534d2b7dc7d757390973a6d172e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1845589Reviewed-by: Matt Menke <mmenke@chromium.org>
Commit-Queue: Abhishek Arya <inferno@chromium.org>
Cr-Commit-Position: refs/heads/master@{#703826}

content/browser/loader/file_url_loader_factory.cc

@@ -436,6 +436,10 @@ class FileURLLoader : public network::mojom::URLLoader {
              LinkFollowingPolicy link_following_policy,
              std::unique_ptr<FileURLLoaderObserver> observer,
              scoped_refptr<net::HttpResponseHeaders> extra_response_headers) {
+    // ClusterFuzz depends on the following VLOG to get resource dependencies.
+    // See crbug.com/715656.
+    VLOG(1) << "FileURLLoader::Start: " << request.url;
+
     network::ResourceResponseHead head;
     head.request_start = base::TimeTicks::Now();
     head.response_start = base::TimeTicks::Now();