Use lossy prefs in the net predictor, and update them more frequently

chrome/browser/net/predictor_browsertest.cc

 // Copyright (c) 2012 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 <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
 #include <memory>
 #include <set>
@@ skipping 1341 matching lines @@
   LearnAboutInitialNavigation(startup_url_);
   // The target URL will have an expected connection count of 2 after this call.
   InstallPredictorObserver(referring_url_, target_url_);
   LearnFromNavigation(referring_url_, target_url_);
 
   // In order to reduce the expected connection count < .8, issue predictions 3
   // times. 2 * .66^3 ~= .58.
   PrepareFrameSubresources(referring_url_);
   PrepareFrameSubresources(referring_url_);
   PrepareFrameSubresources(referring_url_);
+
+  // The onload event is required to persist prefs.
+  ui_test_utils::NavigateToURL(browser(), referring_url_);
 }
 
 IN_PROC_BROWSER_TEST_F(PredictorBrowserTest, ShutdownStartupCyclePreresolve) {
   // 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.
   InstallPredictorObserver(referring_url_, target_url_);
   LearnFromNavigation(referring_url_, target_url_);
+
+  // The onload event is required to persist prefs.
+  ui_test_utils::NavigateToURL(browser(), referring_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);
@@ skipping 159 matching lines @@
   // Second navigation to content with an img.
   std::string img_content =
       "<img src=\"" + preconnect_url.spec() + "test.gif\">";
   NavigateToDataURLWithContent(img_content);
   connection_listener_->WaitUntilFirstConnectionRead();
   EXPECT_EQ(2u, connection_listener_->GetAcceptedSocketCount());
   EXPECT_EQ(1u, connection_listener_->GetReadSocketCount());
 }
 
 }  // namespace chrome_browser_net