Ensure RenderViewHost is not shut down until a screenshot of the page is taken.

chrome/browser/renderer_host/render_process_host_chrome_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 "base/command_line.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/devtools/devtools_window.h"
 #include "chrome/browser/search/search.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_commands.h"
 #include "chrome/browser/ui/singleton_tabs.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/url_constants.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 "content/public/browser/notification_service.h"
 #include "content/public/browser/render_process_host.h"
+#include "content/public/browser/render_process_host_observer.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/render_widget_host_iterator.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_observer.h"
+#include "content/public/test/browser_test_utils.h"
 
 using content::RenderViewHost;
 using content::RenderWidgetHost;
 using content::WebContents;
 
 namespace {
 
 int RenderProcessHostCount() {
   content::RenderProcessHost::iterator hosts =
       content::RenderProcessHost::AllHostsIterator();
@@ skipping 70 matching lines @@
   // in a process of that type, even if that means creating a new process.
   void TestProcessOverflow() {
     int tab_count = 1;
     int host_count = 1;
     WebContents* tab1 = NULL;
     WebContents* tab2 = NULL;
     content::RenderProcessHost* rph1 = NULL;
     content::RenderProcessHost* rph2 = NULL;
     content::RenderProcessHost* rph3 = NULL;
 
-    // Change the first tab to be the omnibox page (TYPE_WEBUI).
+    EXPECT_EQ(host_count, RenderProcessHostCount());
+    ASSERT_EQ(tab_count, browser()->tab_strip_model()->count());
+
+    tab1 = browser()->tab_strip_model()->GetWebContentsAt(tab_count - 1);
+    content::RenderProcessHostWatcher process_watcher(
+        tab1->GetRenderProcessHost(),
+        content::RenderProcessHostWatcher::WATCH_FOR_HOST_DESTRUCTION);
+
+    // Change the first tab to be the omnibox page (TYPE_WEBUI). The navigation
+    // should terminate the existing process.
     GURL omnibox(chrome::kChromeUIOmniboxURL);
     ui_test_utils::NavigateToURL(browser(), omnibox);
+    // Wait for the RPH of the previous page (i.e. starting page) to be
+    // destroyed. The host does not get destroyed until the screenshot of the
+    // page is taken, which may happen after the navigation completes.
+    process_watcher.Wait();
     EXPECT_EQ(tab_count, browser()->tab_strip_model()->count());
     tab1 = browser()->tab_strip_model()->GetWebContentsAt(tab_count - 1);
     rph1 = tab1->GetRenderProcessHost();
     EXPECT_EQ(omnibox, tab1->GetURL());
     EXPECT_EQ(host_count, RenderProcessHostCount());
 
     // Create a new TYPE_TABBED tab.  It should be in its own process.
     GURL page1("data:text/html,hello world1");
 
     ui_test_utils::WindowedTabAddedNotificationObserver observer1(
@@ skipping 70 matching lines @@
 IN_PROC_BROWSER_TEST_F(ChromeRenderProcessHostTest, ProcessPerTab) {
   // Set max renderers to 1 to force running out of processes.
   content::RenderProcessHost::SetMaxRendererProcessCount(1);
 
   CommandLine& parsed_command_line = *CommandLine::ForCurrentProcess();
   parsed_command_line.AppendSwitch(switches::kProcessPerTab);
 
   int tab_count = 1;
   int host_count = 1;
 
+  EXPECT_EQ(tab_count, browser()->tab_strip_model()->count());
+  EXPECT_EQ(host_count, RenderProcessHostCount());
+
+  WebContents* tab1 =
+      browser()->tab_strip_model()->GetWebContentsAt(tab_count - 1);
+  content::RenderProcessHostWatcher process_watcher(
+      tab1->GetRenderProcessHost(),
+      content::RenderProcessHostWatcher::WATCH_FOR_HOST_DESTRUCTION);
+
   // Change the first tab to be the new tab page (TYPE_WEBUI).
   GURL omnibox(chrome::kChromeUIOmniboxURL);
   ui_test_utils::NavigateToURL(browser(), omnibox);
+  // Wait for the RPH of the previous page (i.e. starting page) to be
+  // destroyed. The host does not get destroyed until the screenshot of the
+  // page is taken, which may happen after the navigation completes.
+  process_watcher.Wait();
   EXPECT_EQ(tab_count, browser()->tab_strip_model()->count());
   EXPECT_EQ(host_count, RenderProcessHostCount());
 
   // Create a new TYPE_TABBED tab.  It should be in its own process.
   GURL page1("data:text/html,hello world1");
   ui_test_utils::WindowedTabAddedNotificationObserver observer1(
       content::NotificationService::AllSources());
   chrome::ShowSingletonTab(browser(), page1);
   observer1.Wait();
   tab_count++;
@@ skipping 249 matching lines @@
       chrome::NOTIFICATION_BROWSER_CLOSED,
       content::NotificationService::AllSources());
 
   // Kill the renderer process, simulating a crash. This should the ProcessDied
   // method to be called. Alternatively, RenderProcessHost::OnChannelError can
   // be called to directly force a call to ProcessDied.
   base::KillProcess(wc1->GetRenderProcessHost()->GetHandle(), -1, true);
 
   observer.Wait();
 }