Allow writing browser_tests that involve a restart. The way to do this:

chrome/test/base/in_process_browser_test.h

 // 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.
 
 #ifndef CHROME_TEST_BASE_IN_PROCESS_BROWSER_TEST_H_
 #define CHROME_TEST_BASE_IN_PROCESS_BROWSER_TEST_H_
 
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 62 matching lines @@
 //
 // TearDownInProcessBrowserTestFixture() is called after BrowserMain() exits to
 // cleanup things setup for running the browser.
 //
 // By default InProcessBrowserTest creates a single Browser (as returned from
 // the CreateBrowser method). You can obviously create more as needed.
 
 // InProcessBrowserTest disables the sandbox when running.
 //
 // See ui_test_utils for a handful of methods designed for use with this class.
+//
+// It's possible to write browser tests that span a restart by splitting each
+// run of the browser process into a separate test. Example:
+//
+// IN_PROC_BROWSER_TEST_F(Foo, PRE_Bar) {
+//   do something
+// }
+//
+// IN_PROC_BROWSER_TEST_F(Foo, Bar) {
+//   verify something persisted from before
+// }
+//
+//  This is recursive, so PRE_PRE_Bar would run before PRE_BAR.
 class InProcessBrowserTest : public BrowserTestBase {
  public:
   InProcessBrowserTest();
   virtual ~InProcessBrowserTest();
 
   // Configures everything for an in process browser test, then invokes
   // BrowserMain. BrowserMain ends up invoking RunTestOnMainThreadLoop.
   virtual void SetUp() OVERRIDE;
 
   // Restores state configured in SetUp.
@@ skipping 114 matching lines @@
 #if defined(OS_CHROMEOS)
   chromeos::ScopedStubCrosEnabler stub_cros_enabler_;
 #endif  // defined(OS_CHROMEOS)
 
 #if defined(OS_MACOSX)
   base::mac::ScopedNSAutoreleasePool* autorelease_pool_;
 #endif  // OS_MACOSX
 };
 
 #endif  // CHROME_TEST_BASE_IN_PROCESS_BROWSER_TEST_H_