Lazy load default app icon in LauncherModel. (Bug 11203738)

Change-Id: I397b532f247309de9ae5636b51f125f639966696
diff --git a/src/com/android/launcher3/LauncherModel.java b/src/com/android/launcher3/LauncherModel.java
index 7e1442d..aad768d 100644
--- a/src/com/android/launcher3/LauncherModel.java
+++ b/src/com/android/launcher3/LauncherModel.java
@@ -186,9 +186,6 @@
         mBgAllAppsList = new AllAppsList(iconCache, appFilter);
         mIconCache = iconCache;
 
-        mDefaultIcon = Utilities.createIconBitmap(
-                mIconCache.getFullResDefaultActivityIcon(), context);
-
         final Resources res = context.getResources();
         Configuration config = res.getConfiguration();
         mPreviousConfigMcc = config.mcc;
@@ -400,6 +397,11 @@
     }
 
     public Bitmap getFallbackIcon() {
+        if (mDefaultIcon == null) {
+            final Context context = LauncherAppState.getInstance().getContext();
+            mDefaultIcon = Utilities.createIconBitmap(
+                    mIconCache.getFullResDefaultActivityIcon(), context);
+        }
         return Bitmap.createBitmap(mDefaultIcon);
     }