[Tab Metrics] Added TabManager.SessionRestore.SwitchToTab UMA.

chrome/browser/resource_coordinator/tab_manager_unittest.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 "chrome/browser/resource_coordinator/tab_manager.h"
 
 #include <algorithm>
 #include <map>
 #include <memory>
 #include <vector>
 
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/field_trial.h"
 #include "base/strings/string16.h"
+#include "base/test/histogram_tester.h"
 #include "base/test/mock_entropy_provider.h"
 #include "base/test/simple_test_tick_clock.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/resource_coordinator/tab_manager_web_contents_data.h"
 #include "chrome/browser/resource_coordinator/tab_stats.h"
 #include "chrome/browser/sessions/tab_loader.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
@@ skipping 567 matching lines @@
 
   TabLoader::RestoreTabs(restored_tabs, base::TimeTicks());
   EXPECT_TRUE(tab_manager->IsSessionRestoreLoadingTabs());
 
   WebContentsTester::For(test_contents.get())
       ->NavigateAndCommit(GURL("about:blank"));
   WebContentsTester::For(test_contents.get())->TestSetIsLoading(false);
   EXPECT_FALSE(tab_manager->IsSessionRestoreLoadingTabs());
 }
 
+TEST_F(TabManagerTest, HistogramsSessionRestoreSwitchToTab) {
+  const char kHistogramName[] = "TabManager.SessionRestore.SwitchToTab";
+
+  TabManager tab_manager;
+  WebContents* tab = CreateWebContents();
+  auto* data = tab_manager.GetWebContentsData(tab);
+
+  base::HistogramTester histograms;
+  histograms.ExpectTotalCount(kHistogramName, 0);
+
+  data->SetTabLoadingState(TAB_IS_LOADING);
+  tab_manager.RecordSwitchToTab(tab);
+  tab_manager.RecordSwitchToTab(tab);
+
+  // Nothing should happen until we're in a session restore
+  histograms.ExpectTotalCount(kHistogramName, 0);
+
+  tab_manager.OnSessionRestoreStartedLoadingTabs();
+
+  data->SetTabLoadingState(TAB_IS_NOT_LOADING);
+  tab_manager.RecordSwitchToTab(tab);
+  tab_manager.RecordSwitchToTab(tab);
+  histograms.ExpectTotalCount(kHistogramName, 2);
+  histograms.ExpectBucketCount(kHistogramName, TAB_IS_NOT_LOADING, 2);
+
+  data->SetTabLoadingState(TAB_IS_LOADING);
+  tab_manager.RecordSwitchToTab(tab);
+  tab_manager.RecordSwitchToTab(tab);
+  tab_manager.RecordSwitchToTab(tab);
+
+  histograms.ExpectTotalCount(kHistogramName, 5);
+  histograms.ExpectBucketCount(kHistogramName, TAB_IS_NOT_LOADING, 2);
+  histograms.ExpectBucketCount(kHistogramName, TAB_IS_LOADING, 3);
+
+  data->SetTabLoadingState(TAB_IS_LOADED);
+  tab_manager.RecordSwitchToTab(tab);
+  tab_manager.RecordSwitchToTab(tab);
+  tab_manager.RecordSwitchToTab(tab);
+  tab_manager.RecordSwitchToTab(tab);
+
+  histograms.ExpectTotalCount(kHistogramName, 9);
+  histograms.ExpectBucketCount(kHistogramName, TAB_IS_NOT_LOADING, 2);
+  histograms.ExpectBucketCount(kHistogramName, TAB_IS_LOADING, 3);
+  histograms.ExpectBucketCount(kHistogramName, TAB_IS_LOADED, 4);
+}
+
 }  // namespace resource_coordinator