Add a test that is a repro case for bug 444945.

chrome/browser/task_manager/task_manager_browsertest.cc

Index: chrome/browser/task_manager/task_manager_browsertest.cc
diff --git a/chrome/browser/task_manager/task_manager_browsertest.cc b/chrome/browser/task_manager/task_manager_browsertest.cc
index 25dc0ecd162f93a733268a0e289bb749477ffaeb..2b6dc89dd8dc0fb237f0835725e990e5384b1b49 100644
--- a/chrome/browser/task_manager/task_manager_browsertest.cc
+++ b/chrome/browser/task_manager/task_manager_browsertest.cc
@@ -6,6 +6,7 @@
 
 #include "base/files/file_path.h"
 #include "base/strings/stringprintf.h"
+#include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/devtools/devtools_window_testing.h"
@@ -206,6 +207,61 @@ IN_PROC_BROWSER_TEST_F(TaskManagerBrowserTest, KillTab) {
   ASSERT_NO_FATAL_FAILURE(WaitForTaskManagerRows(2, MatchAnyTab()));
 }
 
+// Test for http://crbug.com/444722, which is not fixed yet.
+IN_PROC_BROWSER_TEST_F(TaskManagerBrowserTest,
+                       DISABLED_NavigateAwayFromHungRenderer) {
+  host_resolver()->AddRule("*", "127.0.0.1");
+  ASSERT_TRUE(embedded_test_server()->InitializeAndWaitUntilReady());
+  content::SetupCrossSiteRedirector(embedded_test_server());

[nasko, 2014/12/23 23:44:04]

nit: You don't need the content::SetupCrossSiteRedirector call as you use the
GetURL to get the proper cross-site URL. 

[ncarter (slow), 2014/12/23 23:54:42]

Good call.

+  ShowTaskManager();
+
+  ASSERT_NO_FATAL_FAILURE(WaitForTaskManagerRows(1, MatchAboutBlankTab()));
+  ASSERT_NO_FATAL_FAILURE(WaitForTaskManagerRows(1, MatchAnyTab()));
+
+  GURL url1(embedded_test_server()->GetURL("/title2.html"));
+  GURL url2(embedded_test_server()->GetURL("/title3.html"));
+  GURL url3(embedded_test_server()->GetURL("a.com", "/iframe.html"));
+
+  // Open a new tab and make sure the task manager notices it.
+  AddTabAtIndex(0, url1, ui::PAGE_TRANSITION_TYPED);
+  ASSERT_NO_FATAL_FAILURE(
+      WaitForTaskManagerRows(1, MatchTab("Title Of Awesomeness")));
+  ASSERT_NO_FATAL_FAILURE(WaitForTaskManagerRows(1, MatchAboutBlankTab()));
+  ASSERT_NO_FATAL_FAILURE(WaitForTaskManagerRows(2, MatchAnyTab()));
+  WebContents* tab1 = browser()->tab_strip_model()->GetActiveWebContents();
+
+  // Initiate a navigation that will create a new WebContents in the same
+  // SiteInstace...
+  content::WebContentsAddedObserver web_contents_added_observer;
+  tab1->GetMainFrame()->ExecuteJavaScriptForTests(
+      base::ASCIIToUTF16("window.open('title3.html', '_blank');"));
+  // ... then immediately hang the renderer so that title3.html can't load.
+  tab1->GetMainFrame()->ExecuteJavaScript(base::ASCIIToUTF16("while(1);"));

[nasko, 2014/12/23 23:44:04]

Wouldn't it be flaky to send these two as separate JS scripts? What happens if
title3.html has completed loading before the while(1) arrives?

[ncarter (slow), 2014/12/23 23:54:42]

Because WebContentses are created on the UI thread, and we are on the UI thread,
it's not possible for the tab2 WebContents to be created until we run the
message loop, which doesn't happen until line 242, after both scripts have
happened. So I think the load can't even really get started until the while(1)
script msg is in the IPC queue. Does that make sense to you?

[nasko, 2014/12/24 00:22:57]

Yes, thanks for the explanation.
Yeah, makes sense. Though the load can start, since it happens on the IO thread
in the browser, but cannot really commit since the while(1) will lock up the UI
thread in the renderer. Neat!

+
+  // Blocks until a new WebContents appears.
+  WebContents* tab2 = web_contents_added_observer.GetWebContents();
+
+  // Make sure the new WebContents is in tab1's hung renderer process.
+  ASSERT_NE(nullptr, tab2);
+  ASSERT_NE(tab1, tab2);
+  ASSERT_EQ(tab1->GetMainFrame()->GetProcess(),
+            tab2->GetMainFrame()->GetProcess())
+      << "New WebContents must be in the same process as the old WebContents, "
+      << "so that the new tab doesn't finish loading (what this test is all "
+      << "about)";
+  ASSERT_EQ(tab1->GetSiteInstance(), tab2->GetSiteInstance())
+      << "New WebContents must initially be in the same site instance as the "
+      << "old WebContents";
+
+  // Now navigate this tab to a different site. This should wind up in a
+  // different renderer process, so it should complete and show up in the task
+  // manager.
+  tab2->OpenURL(content::OpenURLParams(url3, content::Referrer(), CURRENT_TAB,
+                                       ui::PAGE_TRANSITION_TYPED, false));
+
+  ASSERT_NO_FATAL_FAILURE(WaitForTaskManagerRows(1, MatchTab("iframe test")));
+}
+
 IN_PROC_BROWSER_TEST_F(TaskManagerBrowserTest, NoticePanel) {
   ASSERT_TRUE(LoadExtension(
       test_data_dir_.AppendASCII("good").AppendASCII("Extensions")