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

chrome/browser/ui/views/auto_keep_alive.cc

 // Copyright 2014 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 "chrome/browser/ui/views/auto_keep_alive.h"
 
-#include "chrome/browser/lifetime/application_lifetime.h"
+#include "chrome/browser/lifetime/browser_keep_alive.h"
 #include "chrome/browser/ui/host_desktop.h"
 
-AutoKeepAlive::AutoKeepAlive(gfx::NativeWindow window)
-    : keep_alive_available_(false) {
+AutoKeepAlive::AutoKeepAlive(gfx::NativeWindow window) {
   // In case of aura we want default to be keep alive not available for ash
   // because ash has keep alive set and we don't want additional keep alive
   // count.
   chrome::HostDesktopType desktop_type =
       window ? chrome::GetHostDesktopTypeForNativeWindow(window)
              : chrome::GetActiveDesktop();
   if (desktop_type != chrome::HOST_DESKTOP_TYPE_ASH) {

[sky, 2015/10/07 17:27:24]

nit: no {}

-    keep_alive_available_ = true;
-    chrome::IncrementKeepAliveCount();
+    keep_alive_.reset(new browser_lifetime::ScopedKeepAlive);
   }
 }
 
 AutoKeepAlive::~AutoKeepAlive() {
-  if (keep_alive_available_)
-    chrome::DecrementKeepAliveCount();
+  keep_alive_.reset();

[sky, 2015/10/07 17:27:24]

Shouldn't be necessary as this is the destructor.

 }