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

chrome/browser/ui/panels/panel.h

Index: chrome/browser/ui/panels/panel.h
diff --git a/chrome/browser/ui/panels/panel.h b/chrome/browser/ui/panels/panel.h
index a9bd1b3305281a78600b73388fdbfc0b7abeca26..113ce8753301e19eb48fffa522634f5c315f279b 100644
--- a/chrome/browser/ui/panels/panel.h
+++ b/chrome/browser/ui/panels/panel.h
@@ -30,6 +30,10 @@ class PanelManager;
 class Profile;
 class StackedPanelCollection;
 
+namespace browser_lifetime {
+class ScopedKeepAlive;
+}
+
 namespace content {
 class WebContents;
 struct NativeWebKeyboardEvent;
@@ -403,6 +407,10 @@ class Panel : public ui::BaseWindow,
   scoped_ptr<extensions::WindowController> extension_window_controller_;
   scoped_ptr<PanelHost> panel_host_;
 
+#if !defined(USE_AURA)
+  scoped_ptr<browser_lifetime::ScopedKeepAlive> keep_alive_;
+#endif
+
   // Icon showed in the task bar.
   gfx::Image app_icon_;