Add an arbitrary delay before unloading lazy background pages.

chrome/common/chrome_switches.h

Index: chrome/common/chrome_switches.h
diff --git a/chrome/common/chrome_switches.h b/chrome/common/chrome_switches.h
index d33c764d2a32ba6a2938cc416f33db88292e5170..ddf5f1c56faaa5233035fdbb941bebf47d2aa163 100644
--- a/chrome/common/chrome_switches.h
+++ b/chrome/common/chrome_switches.h
@@ -18,7 +18,8 @@ namespace switches {
 // -----------------------------------------------------------------------------
 // Can't find the switch you are looking for? Try looking in
 // ui/gfx/gl/gl_switches.cc or base/base_switches.cc or
-// content/common/content_switches.cc or media/base/media_switches.cc instead.
+// content/public/common/content_switches.cc or media/base/media_switches.cc
+// instead.
 // -----------------------------------------------------------------------------
 
 // All switches in alphabetical order. The switches should be documented
@@ -178,6 +179,8 @@ extern const char kEnableWatchdog[];
 extern const char kEnableWebsiteSettings[];
 extern const char kEnableWebSocketOverSpdy[];
 extern const char kEnableWebStoreLink[];
+extern const char kEventPageIdleTime[];
+extern const char kEventPageUnloadingTime[];
 extern const char kExperimentalSpellcheckerFeatures[];
 extern const char kExplicitlyAllowedPorts[];
 extern const char kExtensionProcess[];