Clear browsing data from ContentSuggestionService only if exists.

Currently, we instantiate the service in BrowsingDataRemover even when
it does not exist, yet. This means that we instantiate it on non-android
platforms, in unit-tests, etc.

This CL changes the logic so that the service is accessed only if it has
been created previously. This way, the BrowsingDataRemover respects the
start-up logic that decides whether to create the service or not.

BUG=647222

Review-Url: https://codereview.chromium.org/2342673004
Cr-Commit-Position: refs/heads/master@{#419141}

chrome/browser/browsing_data/browsing_data_remover.cc

@@ -522,7 +522,7 @@ void BrowsingDataRemover::RemoveImpl(
     }
 
     ntp_snippets::ContentSuggestionsService* content_suggestions_service =
-        ContentSuggestionsServiceFactory::GetForProfile(profile_);
+        ContentSuggestionsServiceFactory::GetForProfileIfExists(profile_);
     if (content_suggestions_service) {
       content_suggestions_service->ClearHistory(delete_begin_, delete_end_,
                                                 filter);
@@ -1016,7 +1016,7 @@ void BrowsingDataRemover::RemoveImpl(
                    weak_ptr_factory_.GetWeakPtr()));
 
     ntp_snippets::ContentSuggestionsService* content_suggestions_service =
-        ContentSuggestionsServiceFactory::GetForProfile(profile_);
+        ContentSuggestionsServiceFactory::GetForProfileIfExists(profile_);
     if (content_suggestions_service)
       content_suggestions_service->ClearAllCachedSuggestions();
   }

chrome/browser/ntp_snippets/content_suggestions_service_factory.cc

@@ -184,6 +184,13 @@ ContentSuggestionsService* ContentSuggestionsServiceFactory::GetForProfile(
       GetInstance()->GetServiceForBrowserContext(profile, true));
 }
 
+// static
+ContentSuggestionsService*
+ContentSuggestionsServiceFactory::GetForProfileIfExists(Profile* profile) {
+  return static_cast<ContentSuggestionsService*>(
+      GetInstance()->GetServiceForBrowserContext(profile, false));
+}
+
 ContentSuggestionsServiceFactory::ContentSuggestionsServiceFactory()
     : BrowserContextKeyedServiceFactory(
           "ContentSuggestionsService",

chrome/browser/ntp_snippets/content_suggestions_service_factory.h

@@ -27,6 +27,8 @@ class ContentSuggestionsServiceFactory
   static ContentSuggestionsServiceFactory* GetInstance();
   static ntp_snippets::ContentSuggestionsService* GetForProfile(
       Profile* profile);
+  static ntp_snippets::ContentSuggestionsService* GetForProfileIfExists(
+      Profile* profile);
 
  private:
   friend struct base::DefaultSingletonTraits<ContentSuggestionsServiceFactory>;

components/ntp_snippets/ntp_snippets_service.cc

@@ -978,6 +978,12 @@ void NTPSnippetsService::EnterState(State state) {
     case State::READY: {
       DCHECK(state_ == State::NOT_INITED || state_ == State::DISABLED);
 
+      // TODO(jkrcal): fetching snippets automatically upon creation of this
+      // lazily created service can cause troubles, e.g. in unittests where
+      // network I/O is not allowed.
+      // Either add a DCHECK here that we actually are allowed to do network I/O
+      // or change the logic so that some explicit call is always needed for the
+      // network request.
       bool fetch_snippets =
           categories_[articles_category_].snippets.empty() || fetch_after_load_;
       DVLOG(1) << "Entering state: READY";