Animating docked background in sync with shelf

ash/launcher/launcher_types.h

Index: ash/launcher/launcher_types.h
diff --git a/ash/launcher/launcher_types.h b/ash/launcher/launcher_types.h
index c60062902a8177020dc30a6797a3f9a4ad3cc1c8..ade2dd95f2063bce069c136c9f31287b2bc77546 100644
--- a/ash/launcher/launcher_types.h
+++ b/ash/launcher/launcher_types.h
@@ -21,6 +21,9 @@ ASH_EXPORT extern const int kLauncherPreferredSize;
 // Max alpha of the launcher background.
 ASH_EXPORT extern const int kLauncherBackgroundAlpha;
 
+// Animation duration for switching black shelf and dock background on and off.
+ASH_EXPORT extern const int kTimeToSwitchBackgroundMs;
+
 // Type the LauncherItem represents.
 enum LauncherItemType {
   // Represents a running app panel.