Implement ClearHistory for all ntp_snippets providers

components/ntp_snippets/ntp_snippets_service_unittest.cc

Index: components/ntp_snippets/ntp_snippets_service_unittest.cc
diff --git a/components/ntp_snippets/ntp_snippets_service_unittest.cc b/components/ntp_snippets/ntp_snippets_service_unittest.cc
index 974f2e8f4550dfe78d0cacc9c6c5cc4552fd64ab..21cec301a289adc1a4cd8e2d4a97633db17d80b6 100644
--- a/components/ntp_snippets/ntp_snippets_service_unittest.cc
+++ b/components/ntp_snippets/ntp_snippets_service_unittest.cc
@@ -864,4 +864,23 @@ TEST_F(NTPSnippetsServiceTest, EmptyImageReturnedForNonExistentId) {
   EXPECT_TRUE(image.IsEmpty());
 }
 
+TEST_F(NTPSnippetsServiceTest, NukeAllSnippetsRemovesAllSuggestions) {
+  auto service = MakeSnippetsService();
+
+  std::string first_snippet = GetSnippetWithUrl("http://url1.com");
+  std::string second_snippet = GetSnippetWithUrl("http://url2.com");
+  std::string json_str = GetTestJson({first_snippet, second_snippet});
+  LoadFromJSONString(service.get(), json_str);
+  ASSERT_THAT(service->GetSnippetsForTesting(), SizeIs(2));
+
+  service->DismissSuggestion(MakeUniqueID(*service, "http://url1.com"));
+  ASSERT_THAT(service->GetSnippetsForTesting(), SizeIs(1));
+  ASSERT_THAT(service->dismissed_snippets_, SizeIs(1));
+
+  service->NukeAllSnippets();

[Marc Treib, 2016/09/01 14:11:20]

Call ClearHistory instead, so you call a public API method rather than a private
one (which is an implementation details that the test shouldn't have to know
about)?

[vitaliii, 2016/09/01 14:45:15]

Done.

+
+  EXPECT_THAT(service->GetSnippetsForTesting(), IsEmpty());
+  EXPECT_THAT(service->dismissed_snippets_, IsEmpty());
+}
+
 }  // namespace ntp_snippets