Fix two URLRequestJob subclasses that didn't support cancellation

components/about_handler/url_request_about_job.cc

Index: components/about_handler/url_request_about_job.cc
diff --git a/components/about_handler/url_request_about_job.cc b/components/about_handler/url_request_about_job.cc
index 880685a1b8d3654deaeab8070a91da22948033ab..fcefc87f195a6475152c8431d01681f3481e4d22 100644
--- a/components/about_handler/url_request_about_job.cc
+++ b/components/about_handler/url_request_about_job.cc
@@ -30,6 +30,11 @@ void URLRequestAboutJob::Start() {
       base::Bind(&URLRequestAboutJob::StartAsync, weak_factory_.GetWeakPtr()));
 }
 
+void URLRequestAboutJob::Kill() {
+  URLRequestJob::Kill();
+  weak_factory_.InvalidateWeakPtrs();

[davidben, 2015/10/08 16:16:36]

Nit: Completely doesn't matter here, but I've seen both orders. My first thought
would be that InvalidateWeakPtrs() should be first, to maintain the invariant
that there is no point in time that the WeakPtr is alive and the URLRequestJob
killed. Kinda like how you destructor subclass before superclass. Thoughts?

(Ditto for the other file.)

[mmenke, 2015/10/08 16:20:42]

Makes sense.  That also the reverse of construction order.  Done (x2).

+}
+
 bool URLRequestAboutJob::GetMimeType(std::string* mime_type) const {
   *mime_type = "text/html";
   return true;