Remove unnecessary return and add bitmap generation ID tracking.

Change-Id: Icf5e0635e789f5ea53268c22fad51cf733b5b1a6
diff --git a/libs/hwui/TextureCache.h b/libs/hwui/TextureCache.h
index 7f95366..bf68061 100644
--- a/libs/hwui/TextureCache.h
+++ b/libs/hwui/TextureCache.h
@@ -37,7 +37,7 @@
     void clear();
 
 private:
-    void generateTexture(SkBitmap* bitmap, Texture* texture);
+    void generateTexture(SkBitmap* bitmap, Texture* texture, bool regenerate = false);
 
     GenerationCache<SkBitmap, Texture> mCache;
 }; // class TextureCache