Inform server of dismissed articles.

components/ntp_snippets/ntp_snippets_service.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/ntp_snippets/ntp_snippets_service.h"
 
 #include <algorithm>
 #include <iterator>
 #include <utility>
 
@@ skipping 247 matching lines @@
 
 void NTPSnippetsService::FetchSnippetsFromHosts(
     const std::set<std::string>& hosts,
     bool interactive_request) {
   if (!ready())
     return;
 
   if (snippets_.empty())
     UpdateCategoryStatus(CategoryStatus::AVAILABLE_LOADING);
 
-  snippets_fetcher_->FetchSnippetsFromHosts(
-      hosts, application_language_code_, kMaxSnippetCount, interactive_request);
+  std::set<std::string> excluded_ids;
+  for (const auto& snippet : dismissed_snippets_) {
+    excluded_ids.insert(snippet->id());

[tschumann, 2016/08/24 16:56:19]

i'm wondering if we should limit those, to say no more than 200 or so. but we
don't have them in chronological order, right?

[sfiera, 2016/08/24 17:08:28]

We have timestamps of creation and expiration, but not the time when we received
them from the server.

In any case, I assume that the server will only honor exclusions up to, say, 50
or so IDs. If, at that point, we stop returning new snippets, it will serve as a
throttle on dismissing more snippets.

[tschumann, 2016/08/24 18:24:07]

Good point! This of course assumes that we don't screw up expiration dates some
day. Would be bad to send large requests just because the articles only expire
in 2033 for some reason ;-)
I might be a bit paranoid though...

[Marc Treib, 2016/08/25 09:01:41]

+1 for some hard limit, just to be safe. I'd put that limit into the fetcher
though, not here.

[sfiera, 2016/08/25 10:39:56]

Done (there, 100).

+  }
+  snippets_fetcher_->FetchSnippetsFromHosts(hosts, application_language_code_,
+                                            excluded_ids, kMaxSnippetCount,
+                                            interactive_request);
 }
 
 void NTPSnippetsService::RescheduleFetching() {
   // The scheduler only exists on Android so far, it's null on other platforms.
   if (!scheduler_)
     return;
 
   if (ready()) {
     base::Time now = base::Time::Now();
     scheduler_->Schedule(
@@ skipping 608 matching lines @@
 void NTPSnippetsService::UpdateCategoryStatus(CategoryStatus status) {
   if (status == category_status_)
     return;
 
   category_status_ = status;
   observer()->OnCategoryStatusChanged(this, provided_category_,
                                       category_status_);
 }
 
 }  // namespace ntp_snippets