Use ash NetworkIconAnimation in NetworkMenuIcon code

ash/system/chromeos/network/network_icon_animation_observer.h

Index: ash/system/chromeos/network/network_icon_animation_observer.h
diff --git a/ash/system/chromeos/network/network_icon_animation_observer.h b/ash/system/chromeos/network/network_icon_animation_observer.h
index 06fc625417cb6e037d68ba13713f274c55eef944..28a5c735d1b61705622a96755eb3c23159853c16 100644
--- a/ash/system/chromeos/network/network_icon_animation_observer.h
+++ b/ash/system/chromeos/network/network_icon_animation_observer.h
@@ -5,11 +5,13 @@
 #ifndef ASH_SYSTEM_CHROMEOS_NETWORK_NETWORK_ICON_ANIMATION_OBSERVER_H_
 #define ASH_SYSTEM_CHROMEOS_NETWORK_NETWORK_ICON_ANIMATION_OBSERVER_H_
 
+#include "ash/ash_export.h"
+
 namespace ash {
 namespace network_icon {
 
 // Observer interface class for animating network icons.
-class AnimationObserver {
+class ASH_EXPORT AnimationObserver {
  public:
   // Called when the image has changed due to animation. The callback should
   // trigger a call to GetImageForNetwork() to retrieve the image.