browser: Start moving application_lifetime.h functions into chrome namespace.

chrome/browser/lifetime/application_lifetime_mac.mm

Index: chrome/browser/lifetime/application_lifetime_mac.mm
diff --git a/chrome/browser/lifetime/application_lifetime_mac.mm b/chrome/browser/lifetime/application_lifetime_mac.mm
index e067f32666c0294555e1d86b7aef2410f358eb5c..9408cfd17a02fbf6ebf3409897ddcca8f5af9e5c 100644
--- a/chrome/browser/lifetime/application_lifetime_mac.mm
+++ b/chrome/browser/lifetime/application_lifetime_mac.mm
@@ -12,7 +12,7 @@
 #include "chrome/browser/browser_shutdown.h"
 #import "chrome/browser/chrome_browser_application_mac.h"
 
-namespace browser {
+namespace chrome {
 
 // At this point, the user is trying to quit (or the system is forcing the
 // application to quit) and all browsers have been successfully closed. The
@@ -28,4 +28,4 @@ void HandleAppExitingForPlatform() {
                     object:NSApp];
 }
 
-}  // namespace browser
+}  // namespace chrome