Don't clear the net predictors prefs on startup

chrome/browser/net/predictor_browsertest.cc

Index: chrome/browser/net/predictor_browsertest.cc
diff --git a/chrome/browser/net/predictor_browsertest.cc b/chrome/browser/net/predictor_browsertest.cc
index 9b0e12d7c3500376d9b758e078cb4a7eb1306db4..35d4c46f4d25efa527f790ca0877c70b4cca4e43 100644
--- a/chrome/browser/net/predictor_browsertest.cc
+++ b/chrome/browser/net/predictor_browsertest.cc
@@ -23,6 +23,9 @@
 #include "base/threading/thread_task_runner_handle.h"
 #include "build/build_config.h"
 #include "chrome/browser/browser_process.h"
+#include "chrome/browser/browsing_data/browsing_data_helper.h"
+#include "chrome/browser/browsing_data/browsing_data_remover.h"
+#include "chrome/browser/browsing_data/browsing_data_remover_factory.h"
 #include "chrome/browser/net/predictor.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
@@ -1362,28 +1365,49 @@ IN_PROC_BROWSER_TEST_F(PredictorBrowserTest,
 }
 
 IN_PROC_BROWSER_TEST_F(PredictorBrowserTest, ShutdownStartupCyclePreresolve) {
-  // Make sure that the Preferences file is actually wiped of all DNS prefetch
-  // related data after start-up.
+  // Make sure this data has been loaded into the Predictor, by inspecting that
+  // the Predictor starts making the expected hostname requests.
+  PrepareFrameSubresources(referring_url_);
+  observer()->WaitUntilHostLookedUp(target_url_);
+
+  // Verify that both urls were requested by the predictor. Note that the
+  // startup URL may be requested before the observer attaches itself.
+  ExpectUrlRequestedFromPredictor(startup_url_);
+  EXPECT_FALSE(observer()->HostFound(target_url_));
+}
+
+IN_PROC_BROWSER_TEST_F(PredictorBrowserTest, PRE_ClearData) {
+  // The target url will have a expected connection count of 2 after this call.

[eroman, 2016/06/25 01:12:53]

nit: url --> URL, and "a expected" --> "an expected"

+  InstallPredictorObserver(referring_url_, target_url_);
+  LearnFromNavigation(referring_url_, target_url_);
+}
+
+// Ensure predictive data is cleared when the history is cleared.
+IN_PROC_BROWSER_TEST_F(PredictorBrowserTest, ClearData) {
   std::string cleared_startup_list;
   std::string cleared_referral_list;
+
+  // The pref should persist after startup.
   GetListFromPrefsAsString(prefs::kDnsPrefetchingStartupList,
                            &cleared_startup_list);
   GetListFromPrefsAsString(prefs::kDnsPrefetchingHostReferralList,
                            &cleared_referral_list);
+  EXPECT_THAT(cleared_referral_list, HasSubstr(referring_url_.host()));
+  EXPECT_THAT(cleared_referral_list, HasSubstr(target_url_.host()));
+
+  // Clear cache which should clear all prefs.
+  BrowsingDataRemover* remover =
+      BrowsingDataRemoverFactory::GetForBrowserContext(browser()->profile());
+  remover->Remove(BrowsingDataRemover::Unbounded(),
+                  BrowsingDataRemover::REMOVE_HISTORY,
+                  BrowsingDataHelper::UNPROTECTED_WEB);
 
-  EXPECT_THAT(cleared_startup_list, Not(HasSubstr(startup_url_.host())));
+  GetListFromPrefsAsString(prefs::kDnsPrefetchingStartupList,
+                           &cleared_startup_list);
+  GetListFromPrefsAsString(prefs::kDnsPrefetchingHostReferralList,
+                           &cleared_referral_list);
   EXPECT_THAT(cleared_referral_list, Not(HasSubstr(referring_url_.host())));
   EXPECT_THAT(cleared_referral_list, Not(HasSubstr(target_url_.host())));
-
-  // But also make sure this data has been first loaded into the Predictor, by
-  // inspecting that the Predictor starts making the expected hostname requests.
-  PrepareFrameSubresources(referring_url_);
-  observer()->WaitUntilHostLookedUp(target_url_);
-
-  // Verify that both urls were requested by the predictor. Note that the
-  // startup URL may be requested before the observer attaches itself.
-  ExpectUrlRequestedFromPredictor(startup_url_);
-  EXPECT_FALSE(observer()->HostFound(target_url_));
 }
 
 // The predictor should not evict recently used (navigated to) referrers.