Enable wallpaper boot animation for boot into sign in too. Add flag to disable it.

chrome/common/chrome_switches.cc

Index: chrome/common/chrome_switches.cc
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index d0353bf86fa74a0a3cbefd71eccc8b57791da1c4..48f3050bfad8633ecdec8aa2bff0a1b53d756fd2 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -1344,6 +1344,9 @@ const char kTabletUI[]                      = "tablet-ui";
 #endif
 
 #if defined(OS_CHROMEOS)
+// Disables wallpaper boot animation (except of OOBE case).
+const char kDisableBootAnimation[]          = "disable-boot-animation";
+
 // Disables gdata content provider.
 const char kDisableGData[]                  = "disable-gdata";
 
@@ -1388,6 +1391,9 @@ const char kEnableUnsupportedBluetoothDevices[] =
 // Enables the experimental wallpaper picker UI.
 const char kExperimentalWallpaperUI[] = "experimental-wallpaper-ui";
 
+// Passed to Chrome on first boot. Not passed on restart after sign out.
+const char kFirstBoot[] = "first-boot";
+
 // Path for the screensaver used in Kiosk mode
 const char kKioskModeScreensaverPath[]      = "kiosk-mode-screensaver-path";