Notify page load metrics when the app enters the background.

chrome/browser/page_load_metrics/page_load_metrics_browsertest.cc

 // Copyright (c) 2015 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 "base/macros.h"
 #include "base/test/histogram_tester.h"
+#include "chrome/browser/page_load_metrics/metrics_web_contents_observer.h"
 #include "chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/document_write_page_load_metrics_observer.h"
+#include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/test/base/in_process_browser_test.h"
 #include "chrome/test/base/ui_test_utils.h"
 #include "net/test/embedded_test_server/embedded_test_server.h"
 
 class MetricsWebContentsObserverBrowserTest : public InProcessBrowserTest {
  public:
   MetricsWebContentsObserverBrowserTest() {}
   ~MetricsWebContentsObserverBrowserTest() override {}
 
  protected:
   void NavigateToUntrackedUrl() {
     ui_test_utils::NavigateToURL(browser(), GURL(url::kAboutBlankURL));
   }
 
   base::HistogramTester histogram_tester_;
 
   DISALLOW_COPY_AND_ASSIGN(MetricsWebContentsObserverBrowserTest);
 };
 
 IN_PROC_BROWSER_TEST_F(MetricsWebContentsObserverBrowserTest, NoNavigation) {
   ASSERT_TRUE(embedded_test_server()->Start());
 
   histogram_tester_.ExpectTotalCount(internal::kHistogramCommit, 0);
   histogram_tester_.ExpectTotalCount(internal::kHistogramDomContentLoaded, 0);
   histogram_tester_.ExpectTotalCount(internal::kHistogramLoad, 0);
   histogram_tester_.ExpectTotalCount(internal::kHistogramFirstLayout, 0);
 }
 
+IN_PROC_BROWSER_TEST_F(MetricsWebContentsObserverBrowserTest, GetAllObservers) {
+  ASSERT_TRUE(embedded_test_server()->Start());
+
+  ASSERT_FALSE(
+      page_load_metrics::MetricsWebContentsObserver::GetAllObservers().empty());
+
+  TabStripModel* tab_strip_model = browser()->tab_strip_model();
+  content::WebContentsDestroyedWatcher destroyed_watcher(
+      tab_strip_model->GetActiveWebContents());
+  tab_strip_model->CloseAllTabs();
+  destroyed_watcher.Wait();
+
+  ASSERT_TRUE(
+      page_load_metrics::MetricsWebContentsObserver::GetAllObservers().empty());
+}
+
 IN_PROC_BROWSER_TEST_F(MetricsWebContentsObserverBrowserTest, NewPage) {
   ASSERT_TRUE(embedded_test_server()->Start());
 
   ui_test_utils::NavigateToURL(browser(),
                                embedded_test_server()->GetURL("/title1.html"));
   NavigateToUntrackedUrl();
 
   histogram_tester_.ExpectTotalCount(internal::kHistogramDomContentLoaded, 1);
   histogram_tester_.ExpectTotalCount(internal::kHistogramLoad, 1);
   histogram_tester_.ExpectTotalCount(internal::kHistogramFirstLayout, 1);
@@ skipping 166 matching lines @@
   ASSERT_TRUE(embedded_test_server()->Start());
 
   ui_test_utils::NavigateToURL(
       browser(), embedded_test_server()->GetURL(
                      "/page_load_metrics/document_write_no_script.html"));
   NavigateToUntrackedUrl();
 
   histogram_tester_.ExpectTotalCount(
       internal::kHistogramDocWriteBlockParseStartToFirstContentfulPaint, 0);
 }