Remove direct uses of TestingFunctionFactory

Replace them with uses of TestingFactory which is based
on base::Callback<> instead of function pointers.

This converts uses in /chrome/browser/safe_browsing/incident_reporting.

This CL was uploaded by git cl split.

R=robertshield@chromium.org

Bug: 809610
Change-Id: Id58fcdc5a649e33a68effc8e774be09beb930ed0
Reviewed-on: https://chromium-review.googlesource.com/1246169
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Reviewed-by: Greg Thompson <grt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595837}

chrome/browser/safe_browsing/incident_reporting/last_download_finder_unittest.cc

@@ -51,8 +51,7 @@
 
 namespace {
 
-// A BrowserContextKeyedServiceFactory::TestingFactoryFunction that creates a
-// HistoryService for a TestingProfile.
+// A testing factory that creates a HistoryService for a TestingProfile.
 std::unique_ptr<KeyedService> BuildHistoryService(
     content::BrowserContext* context) {
   TestingProfile* profile = static_cast<TestingProfile*>(context);