Introduce a request throttler for limiting requests in mobile NTP.

components/ntp_snippets/request_counter_unittest.cc

+// Copyright 2016 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/request_counter.h"
+
+#include "base/strings/stringprintf.h"
+#include "components/ntp_snippets/pref_names.h"
+#include "components/prefs/testing_pref_service.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace ntp_snippets {
+namespace {
+  const char kTestId[] = "test_id";
+}  // namespace
+
+class RequestCounterTest : public testing::Test {
+ public:
+  RequestCounterTest()
+  : counter_(&test_prefs_, kTestId, 2) {

[Marc Treib, 2016/07/19 09:06:17]

nit: I think this should be indented by four more spaces?

[jkrcal, 2016/07/20 09:40:40]

Done.

+    RequestCounter::RegisterProfilePrefs(test_prefs_.registry(), kTestId);
+  }
+
+ protected:
+  TestingPrefServiceSimple test_prefs_;
+  RequestCounter counter_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(RequestCounterTest);
+};
+
+TEST_F(RequestCounterTest, QuotaExceeded) {
+  EXPECT_TRUE(counter_.IsQuotaAvailable());
+  EXPECT_TRUE(counter_.IsQuotaAvailable());
+  EXPECT_FALSE(counter_.IsQuotaAvailable());
+}
+
+TEST_F(RequestCounterTest, ForcedDoesNotCountInQuota) {
+  EXPECT_TRUE(counter_.IsQuotaAvailable());
+  counter_.ReportForcedRequest();
+  EXPECT_TRUE(counter_.IsQuotaAvailable());
+}
+
+TEST_F(RequestCounterTest, QuotaIsPerDay) {
+  EXPECT_TRUE(counter_.IsQuotaAvailable());
+  EXPECT_TRUE(counter_.IsQuotaAvailable());
+
+  // Now fake the counter to believe the count comes from yesterday.
+  base::Time time_yesterday = base::Time::Now() - base::TimeDelta::FromDays(1);
+  int yesterday =
+      base::TimeDelta::FromMilliseconds(time_yesterday.ToJavaTime()).InDays();
+  test_prefs_.SetInteger(base::StringPrintf(
+      ntp_snippets::prefs::kSnippetQuotaDayFormat, kTestId), yesterday);
+
+
+  EXPECT_TRUE(counter_.IsQuotaAvailable());
+}
+
+}  // namespace ntp_snippets