Rework UMAHistogramHelper and StatisticsDeltaReader into [Chrome]HistogramTester.

chrome/browser/prerender/prerender_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 <deque>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/memory/scoped_vector.h"
 #include "base/memory/weak_ptr.h"
 #include "base/path_service.h"
 #include "base/prefs/pref_service.h"
 #include "base/run_loop.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/test/histogram_tester.h"
 #include "base/test/test_timeouts.h"
 #include "base/values.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_test_util.h"
 #include "chrome/browser/chrome_content_browser_client.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/content_settings/host_content_settings_map.h"
 #include "chrome/browser/extensions/api/web_navigation/web_navigation_api.h"
 #include "chrome/browser/extensions/extension_apitest.h"
@@ skipping 27 matching lines @@
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/browser/ui/tabs/tab_strip_model_observer.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/extensions/extension_constants.h"
 #include "chrome/common/extensions/manifest_handlers/mime_types_handler.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/test/base/in_process_browser_test.h"
 #include "chrome/test/base/test_switches.h"
 #include "chrome/test/base/ui_test_utils.h"
-#include "chrome/test/base/uma_histogram_helper.h"
 #include "content/public/browser/browser_message_filter.h"
 #include "content/public/browser/devtools_agent_host.h"
 #include "content/public/browser/devtools_client_host.h"
 #include "content/public/browser/devtools_manager.h"
 #include "content/public/browser/navigation_controller.h"
 #include "content/public/browser/navigation_entry.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/render_view_host.h"
@@ skipping 1422 matching lines @@
             result));
   }
 
   void RunJS(const char* js) {
     ASSERT_TRUE(content::ExecuteScript(
         GetActiveWebContents(),
         base::StringPrintf("window.domAutomationController.send(%s)",
                            js).c_str()));
   }
 
+  base::HistogramTester* const histogram_tester() {

[Ilya Sherman, 2014/07/16 18:44:46]

You're currently returning a const pointer, in the sense that the pointer value
is const.  That's not very helpful -- the pointer value is a primitive type, and
so would be copied anyway.  What you want is "const base::HistogramTester*" --
equivalently, but less idiomatically, "base::HistogramTester const * -- which
specifies that the pointed-to object is const.

Of course at that point, since the object is never null, you might as well use a
const-reference: "const base::HistogramTester&".

[Mike Lerman, 2014/07/16 19:36:36]

I'd say I hate C++ const, except Java's final isn't much better.

+    return &histograms_;
+  }
+
  protected:
   bool autostart_test_server_;
 
  private:
   // TODO(davidben): Remove this altogether so the tests don't globally assume
   // only one prerender.
   TestPrerenderContents* GetPrerenderContents() const {
     return GetPrerenderContentsFor(dest_url_);
   }
 
@@ skipping 130 matching lines @@
 #endif
   NeverRunsExternalProtocolHandlerDelegate external_protocol_handler_delegate_;
   GURL dest_url_;
   scoped_ptr<net::SpawnedTestServer> https_src_server_;
   bool call_javascript_;
   bool check_load_events_;
   std::string loader_host_override_;
   std::string loader_path_;
   std::string loader_query_;
   Browser* explicitly_set_browser_;
+  base::HistogramTester histograms_;
 };
 
 // Checks that a page is correctly prerendered in the case of a
 // <link rel=prerender> tag and then loaded into a tab in response to a
 // navigation.
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderPage) {
-  UMAHistogramHelper histograms;
-
   PrerenderTestURL("files/prerender/prerender_page.html", FINAL_STATUS_USED, 1);
   EXPECT_EQ(1, GetPrerenderDomContentLoadedEventCountForLinkNumber(0));
-  histograms.Fetch();
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLT", 1);
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLTMatched", 0);
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLTMatchedComplete", 0);
-  histograms.ExpectTotalCount("Prerender.websame_PrerenderNotSwappedInPLT", 1);
+  histogram_tester()->ExpectTotalCount("Prerender.none_PerceivedPLT", 1);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.none_PerceivedPLTMatched", 0);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.none_PerceivedPLTMatchedComplete", 0);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.websame_PrerenderNotSwappedInPLT", 1);
 
   ChannelDestructionWatcher channel_close_watcher;
   channel_close_watcher.WatchChannel(
       GetActiveWebContents()->GetRenderProcessHost());
   NavigateToDestURL();
   channel_close_watcher.WaitForChannelClose();
 
-  histograms.Fetch();
-  histograms.ExpectTotalCount("Prerender.websame_PerceivedPLT", 1);
-  histograms.ExpectTotalCount("Prerender.websame_PerceivedPLTMatched", 1);
-  histograms.ExpectTotalCount(
+  histogram_tester()->ExpectTotalCount("Prerender.websame_PerceivedPLT", 1);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.websame_PerceivedPLTMatched", 1);
+  histogram_tester()->ExpectTotalCount(
       "Prerender.websame_PerceivedPLTMatchedComplete", 1);
 
   ASSERT_TRUE(IsEmptyPrerenderLinkManager());
 }
 
 // Checks that cross-domain prerenders emit the correct histograms.
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderPageCrossDomain) {
-  UMAHistogramHelper histograms;
-
   PrerenderTestURL(GetCrossDomainTestUrl("files/prerender/prerender_page.html"),
                    FINAL_STATUS_USED, 1);
-  histograms.Fetch();
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLT", 1);
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLTMatched", 0);
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLTMatchedComplete", 0);
-  histograms.ExpectTotalCount("Prerender.webcross_PrerenderNotSwappedInPLT", 1);
+  histogram_tester()->ExpectTotalCount("Prerender.none_PerceivedPLT", 1);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.none_PerceivedPLTMatched", 0);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.none_PerceivedPLTMatchedComplete", 0);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.webcross_PrerenderNotSwappedInPLT", 1);
 
   NavigateToDestURL();
-  histograms.Fetch();
-  histograms.ExpectTotalCount("Prerender.webcross_PerceivedPLT", 1);
-  histograms.ExpectTotalCount("Prerender.webcross_PerceivedPLTMatched", 1);
-  histograms.ExpectTotalCount(
+  histogram_tester()->ExpectTotalCount("Prerender.webcross_PerceivedPLT", 1);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.webcross_PerceivedPLTMatched", 1);
+  histogram_tester()->ExpectTotalCount(
       "Prerender.webcross_PerceivedPLTMatchedComplete", 1);
 }
 
 // Checks that pending prerenders launch and receive proper event treatment.
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderPagePending) {
   scoped_ptr<TestPrerender> prerender =
       PrerenderTestURL("files/prerender/prerender_page_pending.html",
                        FINAL_STATUS_USED, 1);
 
   // Navigate to the prerender.
@@ skipping 358 matching lines @@
                    FINAL_STATUS_USED,
                    2);
   NavigateToURL("files/prerender/prerender_page.html");
 }
 
 // Checks that we get the right PPLT histograms for client redirect prerenders
 // and navigations when the referring page is Google.
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest,
                        PrerenderLocationReplaceGWSHistograms) {
   DisableJavascriptCalls();
-  UMAHistogramHelper histograms;
 
   // The loader page should look like Google.
   const std::string kGoogleDotCom("www.google.com");
   SetLoaderHostOverride(kGoogleDotCom);
   set_loader_path("files/prerender/prerender_loader_with_replace_state.html");
 
   GURL dest_url = GetCrossDomainTestUrl(
       "files/prerender/prerender_deferred_image.html");
 
   GURL prerender_url = test_server()->GetURL(
       "files/prerender/prerender_location_replace.html?" +
       net::EscapeQueryParamValue(dest_url.spec(), false) +
       "#prerender");
   GURL::Replacements replacements;
   replacements.SetHostStr(kGoogleDotCom);
   prerender_url = prerender_url.ReplaceComponents(replacements);
 
   // The prerender will not completely load until after the swap, so wait for a
   // title change before calling DidPrerenderPass.
   scoped_ptr<TestPrerender> prerender =
       PrerenderTestURL(prerender_url, FINAL_STATUS_USED, 1);
   WaitForASCIITitle(prerender->contents()->prerender_contents(), kReadyTitle);
   EXPECT_TRUE(DidPrerenderPass(prerender->contents()->prerender_contents()));
   EXPECT_EQ(1, prerender->number_of_loads());
 
-  histograms.Fetch();
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLT", 1);
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLTMatched", 0);
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLTMatchedComplete", 0);
+  histogram_tester()->ExpectTotalCount("Prerender.none_PerceivedPLT", 1);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.none_PerceivedPLTMatched", 0);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.none_PerceivedPLTMatchedComplete", 0);
   // Although there is a client redirect, it is dropped from histograms because
   // it is a Google URL. The target page itself does not load until after the
   // swap.
-  histograms.ExpectTotalCount("Prerender.gws_PrerenderNotSwappedInPLT", 0);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.gws_PrerenderNotSwappedInPLT", 0);
 
   GURL navigate_url = test_server()->GetURL(
       "files/prerender/prerender_location_replace.html?" +
       net::EscapeQueryParamValue(dest_url.spec(), false) +
       "#navigate");
   navigate_url = navigate_url.ReplaceComponents(replacements);
 
   NavigationOrSwapObserver swap_observer(
       current_browser()->tab_strip_model(),
       GetActiveWebContents(), 2);
   current_browser()->OpenURL(OpenURLParams(
       navigate_url, Referrer(), CURRENT_TAB,
       content::PAGE_TRANSITION_TYPED, false));
   swap_observer.Wait();
 
   EXPECT_TRUE(DidDisplayPass(GetActiveWebContents()));
 
-  histograms.Fetch();
-  histograms.ExpectTotalCount("Prerender.gws_PrerenderNotSwappedInPLT", 0);
-  histograms.ExpectTotalCount("Prerender.gws_PerceivedPLT", 1);
-  histograms.ExpectTotalCount("Prerender.gws_PerceivedPLTMatched", 1);
-  histograms.ExpectTotalCount(
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.gws_PrerenderNotSwappedInPLT", 0);
+  histogram_tester()->ExpectTotalCount("Prerender.gws_PerceivedPLT", 1);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.gws_PerceivedPLTMatched", 1);
+  histogram_tester()->ExpectTotalCount(
       "Prerender.gws_PerceivedPLTMatchedComplete", 1);
 
   // The client redirect does /not/ count as a miss because it's a Google URL.
-  histograms.ExpectTotalCount("Prerender.PerceivedPLTFirstAfterMiss", 0);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.PerceivedPLTFirstAfterMiss", 0);
 }
 
 // Checks that client-issued redirects work with prerendering.
 // This version navigates to the final destination page, rather than the
 // page which does the redirection via a mouse click.
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest,
                        PrerenderClientRedirectNavigateToSecondViaClick) {
   GURL prerender_url = test_server()->GetURL(
       CreateClientRedirect("files/prerender/prerender_page.html"));
   GURL destination_url = test_server()->GetURL(
@@ skipping 1185 matching lines @@
   PrerenderTestURL("files/prerender/prerender_xhr_put.html",
                    FINAL_STATUS_WOULD_HAVE_BEEN_USED, 0);
   OpenDestURLViaClick();
 }
 
 // Make sure that the MatchComplete dummy works in the normal case.  Once
 // a prerender is cancelled because of a script, a dummy must be created to
 // account for the MatchComplete case, and it must have a final status of
 // FINAL_STATUS_WOULD_HAVE_BEEN_USED.
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, MatchCompleteDummy) {
-  UMAHistogramHelper histograms;
 
   std::vector<FinalStatus> expected_final_status_queue;
   expected_final_status_queue.push_back(FINAL_STATUS_INVALID_HTTP_METHOD);
   expected_final_status_queue.push_back(FINAL_STATUS_WOULD_HAVE_BEEN_USED);
   PrerenderTestURL("files/prerender/prerender_xhr_put.html",
                    expected_final_status_queue, 1);
-  histograms.Fetch();
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLT", 1);
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLTMatched", 0);
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLTMatchedComplete", 0);
-  histograms.ExpectTotalCount("Prerender.websame_PrerenderNotSwappedInPLT", 1);
+  histogram_tester()->ExpectTotalCount("Prerender.none_PerceivedPLT", 1);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.none_PerceivedPLTMatched", 0);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.none_PerceivedPLTMatchedComplete", 0);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.websame_PrerenderNotSwappedInPLT", 1);
 
   NavigateToDestURL();
-  histograms.Fetch();
-  histograms.ExpectTotalCount("Prerender.websame_PerceivedPLT", 1);
-  histograms.ExpectTotalCount("Prerender.websame_PerceivedPLTMatched", 0);
-  histograms.ExpectTotalCount(
+  histogram_tester()->ExpectTotalCount("Prerender.websame_PerceivedPLT", 1);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.websame_PerceivedPLTMatched", 0);
+  histogram_tester()->ExpectTotalCount(
       "Prerender.websame_PerceivedPLTMatchedComplete", 1);
 }
 
 // Verify that a navigation that hits a MatchComplete dummy while another is in
 // progress does not also classify the previous navigation as a MatchComplete.
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest,
                        MatchCompleteDummyCancelNavigation) {
-  UMAHistogramHelper histograms;
 
   // Arrange for a URL to hang.
   const GURL kNoCommitUrl("http://never-respond.example.com");
   base::FilePath file(FILE_PATH_LITERAL(
       "chrome/test/data/prerender/prerender_page.html"));
   base::RunLoop hang_loop;
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE,
       base::Bind(&CreateHangingFirstRequestInterceptorOnIO, kNoCommitUrl,
                  file, hang_loop.QuitClosure()));
 
   // First, fire a prerender that aborts after it completes its load.
   std::vector<FinalStatus> expected_final_status_queue;
   expected_final_status_queue.push_back(FINAL_STATUS_INVALID_HTTP_METHOD);
   expected_final_status_queue.push_back(FINAL_STATUS_WOULD_HAVE_BEEN_USED);
   PrerenderTestURL("files/prerender/prerender_xhr_put.html",
                    expected_final_status_queue, 1);
-  histograms.Fetch();
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLT", 1);
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLTMatched", 0);
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLTMatchedComplete", 0);
-  histograms.ExpectTotalCount("Prerender.websame_PrerenderNotSwappedInPLT", 1);
+  histogram_tester()->ExpectTotalCount("Prerender.none_PerceivedPLT", 1);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.none_PerceivedPLTMatched", 0);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.none_PerceivedPLTMatchedComplete", 0);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.websame_PrerenderNotSwappedInPLT", 1);
 
   // Open the hanging URL in a new tab. Wait for both the new tab to open and
   // the hanging request to be scheduled.
   ui_test_utils::NavigateToURLWithDisposition(
       current_browser(), kNoCommitUrl, NEW_FOREGROUND_TAB,
       ui_test_utils::BROWSER_TEST_WAIT_FOR_TAB);
   hang_loop.Run();
 
   // Now interrupt that navigation and navigate to the destination URL. This
   // should forcibly complete the previous navigation and also complete a
   // WOULD_HAVE_BEEN_PRERENDERED navigation.
   NavigateToDestURL();
-  histograms.Fetch();
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLT", 2);
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLTMatched", 0);
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLTMatchedComplete", 0);
-  histograms.ExpectTotalCount("Prerender.websame_PerceivedPLT", 1);
-  histograms.ExpectTotalCount("Prerender.websame_PerceivedPLTMatched", 0);
-  histograms.ExpectTotalCount(
+  histogram_tester()->ExpectTotalCount("Prerender.none_PerceivedPLT", 2);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.none_PerceivedPLTMatched", 0);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.none_PerceivedPLTMatchedComplete", 0);
+  histogram_tester()->ExpectTotalCount("Prerender.websame_PerceivedPLT", 1);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.websame_PerceivedPLTMatched", 0);
+  histogram_tester()->ExpectTotalCount(
       "Prerender.websame_PerceivedPLTMatchedComplete", 1);
 }
 
 class PrerenderBrowserTestWithNaCl : public PrerenderBrowserTest {
  public:
   PrerenderBrowserTestWithNaCl() {}
   virtual ~PrerenderBrowserTestWithNaCl() {}
 
   virtual void SetUpCommandLine(CommandLine* command_line) OVERRIDE {
     PrerenderBrowserTest::SetUpCommandLine(command_line);
@@ skipping 362 matching lines @@
   prerenders[1]->WaitForStop();
 
   // Check the referring page only got one copy of the event.
   EXPECT_FALSE(HadPrerenderEventErrors());
 }
 
 // Checks that a deferred redirect to an image is not loaded until the page is
 // visible. Also test the right histogram events are emitted in this case.
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderDeferredImage) {
   DisableJavascriptCalls();
-  UMAHistogramHelper histograms;
 
   // The prerender will not completely load until after the swap, so wait for a
   // title change before calling DidPrerenderPass.
   scoped_ptr<TestPrerender> prerender =
       PrerenderTestURL(
           "files/prerender/prerender_deferred_image.html",
           FINAL_STATUS_USED, 0);
   WaitForASCIITitle(prerender->contents()->prerender_contents(), kReadyTitle);
   EXPECT_EQ(1, GetPrerenderDomContentLoadedEventCountForLinkNumber(0));
   EXPECT_TRUE(DidPrerenderPass(prerender->contents()->prerender_contents()));
   EXPECT_EQ(0, prerender->number_of_loads());
-  histograms.Fetch();
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLT", 1);
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLTMatched", 0);
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLTMatchedComplete", 0);
-  histograms.ExpectTotalCount("Prerender.websame_PrerenderNotSwappedInPLT", 0);
+  histogram_tester()->ExpectTotalCount("Prerender.none_PerceivedPLT", 1);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.none_PerceivedPLTMatched", 0);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.none_PerceivedPLTMatchedComplete", 0);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.websame_PrerenderNotSwappedInPLT", 0);
 
   // Swap.
   NavigationOrSwapObserver swap_observer(current_browser()->tab_strip_model(),
                                          GetActiveWebContents());
   ui_test_utils::NavigateToURLWithDisposition(
       current_browser(), dest_url(), CURRENT_TAB,
       ui_test_utils::BROWSER_TEST_NONE);
   swap_observer.Wait();
 
   // The prerender never observes the final load.
   EXPECT_EQ(0, prerender->number_of_loads());
 
   // Now check DidDisplayPass.
   EXPECT_TRUE(DidDisplayPass(GetActiveWebContents()));
 
-  histograms.Fetch();
-  histograms.ExpectTotalCount("Prerender.websame_PrerenderNotSwappedInPLT", 0);
-  histograms.ExpectTotalCount("Prerender.websame_PerceivedPLT", 1);
-  histograms.ExpectTotalCount("Prerender.websame_PerceivedPLTMatched", 1);
-  histograms.ExpectTotalCount(
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.websame_PrerenderNotSwappedInPLT", 0);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.websame_PerceivedPLT", 1);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.websame_PerceivedPLTMatched", 1);
+  histogram_tester()->ExpectTotalCount(
       "Prerender.websame_PerceivedPLTMatchedComplete", 1);
 }
 
 // Checks that a deferred redirect to an image is not loaded until the
 // page is visible, even after another redirect.
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest,
                        PrerenderDeferredImageAfterRedirect) {
   DisableJavascriptCalls();
 
   // The prerender will not completely load until after the swap, so wait for a
@@ skipping 324 matching lines @@
       base::Bind(&CreateCountingInterceptorOnIO,
                  kPingURL, empty_file, ping_counter.AsWeakPtr()));
 
   PrerenderTestURL("files/prerender/prerender_page.html", FINAL_STATUS_USED, 1);
   OpenDestURLViaClickPing(kPingURL);
 
   ping_counter.WaitForCount(1);
 }
 
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderPPLTNormalNavigation) {
-  UMAHistogramHelper histograms;
 
   GURL url = test_server()->GetURL("files/prerender/prerender_page.html");
   ui_test_utils::NavigateToURL(current_browser(), url);
-  histograms.Fetch();
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLT", 1);
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLTMatched", 0);
-  histograms.ExpectTotalCount("Prerender.none_PerceivedPLTMatchedComplete", 0);
+  histogram_tester()->ExpectTotalCount("Prerender.none_PerceivedPLT", 1);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.none_PerceivedPLTMatched", 0);
+  histogram_tester()->ExpectTotalCount(
+      "Prerender.none_PerceivedPLTMatchedComplete", 0);
 }
 
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest,
                        PrerenderCookieChangeConflictTest) {
   NavigateStraightToURL(
       "files/prerender/prerender_cookie.html?set=1&key=c&value=1");
 
   GURL url = test_server()->GetURL(
       "files/prerender/prerender_cookie.html?set=1&key=c&value=2");
 
@@ skipping 217 matching lines @@
 
   // Navigate to the URL entered.
   omnibox_view->model()->AcceptInput(CURRENT_TAB, false);
 
   // Prerender should be running, but abandoned.
   EXPECT_TRUE(
       GetAutocompleteActionPredictor()->IsPrerenderAbandonedForTesting());
 }
 
 }  // namespace prerender