chrome://snippets-internals page for debugging NTP snippets.

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 38c98f199319b6398624718deb225e539524eac1..0bd1f5f00b4e692531286e69a4783169d5f71463 100644
--- a/components/ntp_snippets/ntp_snippets_service.cc
+++ b/components/ntp_snippets/ntp_snippets_service.cc
@@ -68,7 +68,7 @@ base::TimeDelta GetFetchingIntervalFallback() {
 }
 
 // Extracts the hosts from |suggestions| and returns them in a set.
-std::set<std::string> GetSuggestionsHosts(
+std::set<std::string> GetSuggestionsHostsImpl(
     const SuggestionsProfile& suggestions) {
   std::set<std::string> hosts;
   for (int i = 0; i < suggestions.suggestions_size(); ++i) {
@@ -182,12 +182,39 @@ void NTPSnippetsService::Shutdown() {
 }
 
 void NTPSnippetsService::FetchSnippets() {
-  // |suggestions_service_| can be null in tests.
-  if (!suggestions_service_)
+  FetchSnippetsFromHosts(GetSuggestionsHosts());
+}
+
+void NTPSnippetsService::FetchSnippetsFromHosts(
+    const std::set<std::string>& hosts) {
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kDontRestrict)) {
+    snippets_fetcher_->FetchSnippets(std::set<std::string>());
     return;
+  }
+  if (!hosts.empty())
+    snippets_fetcher_->FetchSnippets(hosts);
+}
+
+void NTPSnippetsService::ClearSnippets() {
+  snippets_.clear();
+
+  StoreSnippetsToPrefs();
+
+  FOR_EACH_OBSERVER(NTPSnippetsServiceObserver, observers_,
+                    NTPSnippetsServiceLoaded());
+}
+
+std::set<std::string> NTPSnippetsService::GetSuggestionsHosts() const {
+  // |suggestions_service_| can be null in tests.
+  if (!suggestions_service_) {
+    std::set<std::string> empty;
+    return empty;

[Marc Treib, 2016/04/14 15:43:44]

Just 
return std::set<std::string>();
?

[jkrcal, 2016/04/14 16:41:01]

Done.

+  }
 
-  FetchSnippetsImpl(GetSuggestionsHosts(
-      suggestions_service_->GetSuggestionsDataFromCache()));
+  // TODO(treib) this should just call GetSnippetHostsFromPrefs
+  return GetSuggestionsHostsImpl(
+      suggestions_service_->GetSuggestionsDataFromCache());
 }
 
 bool NTPSnippetsService::DiscardSnippet(const GURL& url) {
@@ -201,11 +228,21 @@ bool NTPSnippetsService::DiscardSnippet(const GURL& url) {
   snippets_.erase(it);
   StoreDiscardedSnippetsToPrefs();
   StoreSnippetsToPrefs();
+  FOR_EACH_OBSERVER(NTPSnippetsServiceObserver, observers_,
+                    NTPSnippetsServiceLoaded());
   return true;
 }
 
+void NTPSnippetsService::ClearDiscardedSnippets() {
+  discarded_snippets_.clear();
+  StoreDiscardedSnippetsToPrefs();
+  FetchSnippets();
+}
+
 void NTPSnippetsService::AddObserver(NTPSnippetsServiceObserver* observer) {
-  observers_.AddObserver(observer);
+  if (!observers_.HasObserver(observer)) {

[Marc Treib, 2016/04/14 15:43:44]

This shouldn't be here. It's the responsibility of the other object to make sure
it doesn't register itself twice.

[jkrcal, 2016/04/14 16:41:01]

Done.

+    observers_.AddObserver(observer);
+  }
   observer->NTPSnippetsServiceLoaded();
 }
 
@@ -215,7 +252,7 @@ void NTPSnippetsService::RemoveObserver(NTPSnippetsServiceObserver* observer) {
 
 void NTPSnippetsService::OnSuggestionsChanged(
     const SuggestionsProfile& suggestions) {
-  std::set<std::string> hosts = GetSuggestionsHosts(suggestions);
+  std::set<std::string> hosts = GetSuggestionsHostsImpl(suggestions);
   if (hosts == GetSnippetHostsFromPrefs())
     return;
 
@@ -233,7 +270,7 @@ void NTPSnippetsService::OnSuggestionsChanged(
   FOR_EACH_OBSERVER(NTPSnippetsServiceObserver, observers_,
                     NTPSnippetsServiceLoaded());
 
-  FetchSnippetsImpl(hosts);
+  FetchSnippetsFromHosts(hosts);
 }
 
 void NTPSnippetsService::OnSnippetsDownloaded(
@@ -256,17 +293,6 @@ void NTPSnippetsService::OnJsonError(const std::string& snippets_json,
   LOG(WARNING) << "Received invalid JSON (" << error << "): " << snippets_json;
 }
 
-void NTPSnippetsService::FetchSnippetsImpl(
-    const std::set<std::string>& hosts) {
-  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kDontRestrict)) {
-    snippets_fetcher_->FetchSnippets(std::set<std::string>());
-    return;
-  }
-  if (!hosts.empty())
-    snippets_fetcher_->FetchSnippets(hosts);
-}
-
 bool NTPSnippetsService::LoadFromValue(const base::Value& value) {
   const base::DictionaryValue* top_dict = nullptr;
   if (!value.GetAsDictionary(&top_dict))