Cleanup: Pull some browser keep alive functions into its own file.

chrome/browser/sessions/better_session_restore_browsertest.cc

Index: chrome/browser/sessions/better_session_restore_browsertest.cc
diff --git a/chrome/browser/sessions/better_session_restore_browsertest.cc b/chrome/browser/sessions/better_session_restore_browsertest.cc
index 7b15d5ca60bae65a55edd5677938c55daf258c66..8bc565c7c43ccab580750df271da29f96845271d 100644
--- a/chrome/browser/sessions/better_session_restore_browsertest.cc
+++ b/chrome/browser/sessions/better_session_restore_browsertest.cc
@@ -17,6 +17,7 @@
 #include "chrome/browser/defaults.h"
 #include "chrome/browser/infobars/infobar_service.h"
 #include "chrome/browser/lifetime/application_lifetime.h"
+#include "chrome/browser/lifetime/browser_keep_alive.h"
 #include "chrome/browser/prefs/session_startup_pref.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_impl.h"
@@ -147,7 +148,6 @@ class FakeBackgroundModeManager : public BackgroundModeManager {
 
  private:
   bool background_mode_active_;
-
 };
 
 }  // namespace
@@ -314,7 +314,7 @@ class BetterSessionRestoreTest : public InProcessBrowserTest {
     Profile* profile = browser->profile();
 
     // Close the browser.
-    chrome::IncrementKeepAliveCount();
+    browser_lifetime::ScopedKeepAlive keep_alive;
     if (close_all_windows)
       CloseAllBrowsers();
     else
@@ -329,10 +329,7 @@ class BetterSessionRestoreTest : public InProcessBrowserTest {
     // Create a new window, which should trigger session restore.
     ui_test_utils::BrowserAddedObserver window_observer;
     chrome::NewEmptyWindow(profile, chrome::HOST_DESKTOP_TYPE_NATIVE);
-    Browser* new_browser = window_observer.WaitForSingleNewBrowser();
-    chrome::DecrementKeepAliveCount();
-
-    return new_browser;
+    return window_observer.WaitForSingleNewBrowser();
   }
 
   std::string fake_server_address() {
@@ -390,6 +387,7 @@ class ContinueWhereILeftOffTest : public BetterSessionRestoreTest {
     return new_browser;
   }
 
+ private:
   DISALLOW_COPY_AND_ASSIGN(ContinueWhereILeftOffTest);
 };