Fixes that host restriction was sometimes applied even when switched off.

components/ntp_snippets/ntp_snippets_service.cc

Index: components/ntp_snippets/ntp_snippets_service.cc
diff --git a/components/ntp_snippets/ntp_snippets_service.cc b/components/ntp_snippets/ntp_snippets_service.cc
index 555e101213efd53b78add33ac071a137b1e92755..9aa87bc4a50d295f364a289e8819b7edc3f1a110 100644
--- a/components/ntp_snippets/ntp_snippets_service.cc
+++ b/components/ntp_snippets/ntp_snippets_service.cc
@@ -186,7 +186,7 @@ void NTPSnippetsService::Init(bool enabled) {
   enabled_ = enabled;
   if (enabled_) {
     // |suggestions_service_| can be null in tests.
-    if (suggestions_service_) {
+    if (snippets_fetcher_->UseHostRestriction() && suggestions_service_) {

[Marc Treib, 2016/05/17 15:23:58]

Should we (in another CL) make UseHostRestriction (and similarly
UseAuthentication) static, to make it a bit clearer that they can never change
at runtime?

[jkrcal, 2016/05/18 08:30:39]

I agree, in a separate CL.
Heh, I've forgotten to make them public in first place :) I was puzzled because
I did it in https://codereview.chromium.org/1978513002/. I took over all changes
in ntp_snippets_fetcher.h from there to make merging easier.

       suggestions_service_subscription_ = suggestions_service_->AddCallback(
           base::Bind(&NTPSnippetsService::OnSuggestionsChanged,
                      base::Unretained(this)));