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

chrome/browser/ui/apps/chrome_app_delegate.h

Index: chrome/browser/ui/apps/chrome_app_delegate.h
diff --git a/chrome/browser/ui/apps/chrome_app_delegate.h b/chrome/browser/ui/apps/chrome_app_delegate.h
index 1a7ac1f1c5bc15163691981ac6008d50929fed3e..941c71951bb420c1f0f03f7f6345c0848d78151f 100644
--- a/chrome/browser/ui/apps/chrome_app_delegate.h
+++ b/chrome/browser/ui/apps/chrome_app_delegate.h
@@ -14,14 +14,17 @@
 #include "ui/base/window_open_disposition.h"
 #include "ui/gfx/geometry/rect.h"
 
+namespace browser_lifetime {
 class ScopedKeepAlive;
+}
 
 class ChromeAppDelegate : public extensions::AppDelegate,
                           public content::NotificationObserver {
  public:
   // Pass a ScopedKeepAlive to prevent the browser process from shutting down
   // while this object exists.
-  explicit ChromeAppDelegate(scoped_ptr<ScopedKeepAlive> keep_alive);
+  explicit ChromeAppDelegate(
+      scoped_ptr<browser_lifetime::ScopedKeepAlive> keep_alive);
   ~ChromeAppDelegate() override;
 
   static void DisableExternalOpenForTesting();
@@ -76,7 +79,7 @@ class ChromeAppDelegate : public extensions::AppDelegate,
 
   bool has_been_shown_;
   bool is_hidden_;
-  scoped_ptr<ScopedKeepAlive> keep_alive_;
+  scoped_ptr<browser_lifetime::ScopedKeepAlive> keep_alive_;
   scoped_ptr<NewWindowContentsDelegate> new_window_contents_delegate_;
   base::Closure terminating_callback_;
   content::NotificationRegistrar registrar_;