Experiment to disable Prerendering with fast wind-down

chrome/browser/prerender/prerender_unittest.cc

Index: chrome/browser/prerender/prerender_unittest.cc
diff --git a/chrome/browser/prerender/prerender_unittest.cc b/chrome/browser/prerender/prerender_unittest.cc
index c30343e836f38b41161b386ca55538d2f0b02814..42ed22c0b15a24d9e2f5e984dde5304cd10d0fa6 100644
--- a/chrome/browser/prerender/prerender_unittest.cc
+++ b/chrome/browser/prerender/prerender_unittest.cc
@@ -148,6 +148,10 @@ class UnitTestPrerenderManager : public PrerenderManager {
     return prerender_contents;
   }
 
+  bool SetTime(const std::string& time_string) {
+    return base::Time::FromString(time_string.c_str(), &time_);
+  }
+
   void AdvanceTime(TimeDelta delta) {
     time_ += delta;
   }
@@ -1104,6 +1108,65 @@ TEST_F(PrerenderTest, PrerenderNotAllowedOnCellularWithExternalOrigin) {
   EXPECT_FALSE(prerender_contents->prerendering_has_started());
 }
 
+// Checks that the "PrerenderSilence experiment does not disable offline
+// prerendering.
+TEST_F(PrerenderTest, PrerenderSilenceAllowsOffline) {
+  // Set the time to 30 seconds before the experiment expires.
+  ASSERT_TRUE(base::FieldTrialList::CreateFieldTrial(
+      "PrerenderSilence", "ExperimentYes_expires_2016-12-20T00:01:00Z"));
+  ASSERT_TRUE(prerender_manager()->SetTime("2016-12-20T00:00:30Z"));

[mmenke, 2016/08/26 16:44:47]

Do we really want a unit test with an expiration date?  Remember that we run
tests on stable channel, too.

[pasko, 2016/08/26 17:39:31]

I do not follow how release channel can be relevant to a unittest. Can you
elaborate?

The test itself does not expire even if it is run in 2020 because
PrerenderManager::time_ is changed according to the test, not the current time.

[mmenke, 2016/08/26 18:15:40]

Ahh, I missed that.  Channel is relevant because it means a test will live for
months on even after it's been removed from Canary.

+  GURL url("http://www.google.com/");
+  DummyPrerenderContents* prerender_contents =
+      prerender_manager()->CreateNextPrerenderContents(
+          url, ORIGIN_OFFLINE, FINAL_STATUS_MANAGER_SHUTDOWN);
+  std::unique_ptr<PrerenderHandle> prerender_handle =
+      prerender_manager()->AddPrerenderForOffline(url, nullptr, kSize);
+  EXPECT_TRUE(prerender_handle);
+  EXPECT_TRUE(prerender_handle->IsPrerendering());
+  EXPECT_TRUE(prerender_contents->prerendering_has_started());
+  EXPECT_EQ(prerender_contents, prerender_handle->contents());
+  EXPECT_EQ(ORIGIN_OFFLINE, prerender_handle->contents()->origin());
+}
+
+// Checks that the "PrerenderSilence" experiment disables prerendering.
+TEST_F(PrerenderTest, PrerenderSilenceDisallowsNonOffline) {
+  ASSERT_TRUE(base::FieldTrialList::CreateFieldTrial(
+      "PrerenderSilence", "ExperimentYes_expires_2016-12-20T00:02:00Z"));
+  const Origin origins[] = {
+      ORIGIN_GWS_PRERENDER,
+      ORIGIN_OMNIBOX,
+      ORIGIN_NONE,
+      ORIGIN_LINK_REL_PRERENDER_SAMEDOMAIN,
+      ORIGIN_LINK_REL_PRERENDER_CROSSDOMAIN,
+      ORIGIN_EXTERNAL_REQUEST,
+      ORIGIN_INSTANT,
+      ORIGIN_LINK_REL_NEXT,
+      ORIGIN_EXTERNAL_REQUEST_FORCED_CELLULAR,
+  };
+  ASSERT_TRUE(prerender_manager()->SetTime("2016-12-20T00:01:00Z"));
+  for (const Origin& origin : origins) {
+    EXPECT_TRUE(
+        prerender_manager()->IsPrerenderSilenceExperimentForTesting(origin));
+  }
+}
+
+// Checks that prerendering is enabled after expiration of the
+// "PrerenderSilence" experiment.
+TEST_F(PrerenderTest, PrerenderSilenceAllowsAfterExpiration) {
+  ASSERT_TRUE(base::FieldTrialList::CreateFieldTrial(
+      "PrerenderSilence", "ExperimentYes_expires_2016-12-20T00:02:00Z"));
+  GURL url("http://www.google.com/");
+  ASSERT_TRUE(prerender_manager()->SetTime("2016-12-20T00:01:00Z"));
+  prerender_manager()->AdvanceTime(TimeDelta::FromSeconds(60));
+  DummyPrerenderContents* prerender_contents =
+      prerender_manager()->CreateNextPrerenderContents(url, FINAL_STATUS_USED);
+  EXPECT_TRUE(AddSimplePrerender(url));
+  EXPECT_TRUE(prerender_contents->prerendering_has_started());
+  std::unique_ptr<PrerenderContents> entry =
+      prerender_manager()->FindAndUseEntry(url);
+  ASSERT_EQ(prerender_contents, entry.get());
+}
+
 TEST_F(PrerenderTest, PrerenderAllowedForOfflineAndForcedCellular) {
   const Origin origins[] = {
     ORIGIN_EXTERNAL_REQUEST_FORCED_CELLULAR,