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

chrome/browser/metro_viewer/chrome_metro_viewer_process_host_aurawin.cc

Index: chrome/browser/metro_viewer/chrome_metro_viewer_process_host_aurawin.cc
diff --git a/chrome/browser/metro_viewer/chrome_metro_viewer_process_host_aurawin.cc b/chrome/browser/metro_viewer/chrome_metro_viewer_process_host_aurawin.cc
index 4b3f4a65773213c4a6b77d2ff5c5a540455e52b5..fe88c2eb8ea1cc19dc34c82df9b4313a9b841c3b 100644
--- a/chrome/browser/metro_viewer/chrome_metro_viewer_process_host_aurawin.cc
+++ b/chrome/browser/metro_viewer/chrome_metro_viewer_process_host_aurawin.cc
@@ -17,6 +17,7 @@
 #include "chrome/browser/browser_shutdown.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/lifetime/application_lifetime.h"
+#include "chrome/browser/lifetime/browser_keep_alive.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/search_engines/template_url_service_factory.h"
 #include "chrome/browser/ui/ash/ash_init.h"
@@ -73,7 +74,7 @@ ChromeMetroViewerProcessHost::ChromeMetroViewerProcessHost()
     : MetroViewerProcessHost(
           content::BrowserThread::GetMessageLoopProxyForThread(
               content::BrowserThread::IO)) {
-  chrome::IncrementKeepAliveCount();
+  browser_lifetime::IncrementKeepAliveCount();
 }
 
 ChromeMetroViewerProcessHost::~ChromeMetroViewerProcessHost() {
@@ -93,7 +94,7 @@ void ChromeMetroViewerProcessHost::OnChannelError() {
   if (aura::RemoteWindowTreeHostWin::Instance()) {
     aura::RemoteWindowTreeHostWin::Instance()->Disconnected();
 
-    chrome::DecrementKeepAliveCount();
+    browser_lifetime::DecrementKeepAliveCount();
 
     // If browser is trying to quit, we shouldn't reenter the process.
     // TODO(shrikant): In general there seem to be issues with how AttemptExit
@@ -110,7 +111,7 @@ void ChromeMetroViewerProcessHost::OnChannelError() {
     return;
   }
 
-  chrome::DecrementKeepAliveCount();
+  browser_lifetime::DecrementKeepAliveCount();
 
   // This will delete the MetroViewerProcessHost object. Don't access member
   // variables/functions after this call.