Network Error Logging: Move base::Feature check to NetworkContext.

Cronet doesn't support controlling base::Features, so move the
base::Feature to //services/network (in a tiny component, because things
break otherwise), and move the feature check itself to NetworkContext.

(A future change will add an experimental option to Cronet to enable
Reporting and NEL.)

This is a fixed re-land of https://chromium-review.googlesource.com/c/chromium/src/+/858176.

Bug: 799616
Change-Id: I79c8a011c75d6b79a92f9ffe85bf5d53d509dcbc
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_mojo
Reviewed-on: https://chromium-review.googlesource.com/879441
Commit-Queue: Julia Tuttle <[email protected]>
Reviewed-by: Jochen Eisinger <[email protected]>
Reviewed-by: Matt Menke <[email protected]>
Reviewed-by: Bernhard Bauer <[email protected]>
Cr-Commit-Position: refs/heads/master@{#532006}
diff --git a/net/reporting/reporting_service.h b/net/reporting/reporting_service.h
index aa7dc40e..37958702 100644
--- a/net/reporting/reporting_service.h
+++ b/net/reporting/reporting_service.h
@@ -70,6 +70,8 @@
   // about report uploads.
   virtual bool RequestIsUpload(const URLRequest& request) = 0;
 
+  virtual const ReportingPolicy& GetPolicy() const = 0;
+
  protected:
   ReportingService() {}