Merged op dispatch in OpReorderer

bug:22480459

Also switches std::functions to function pointers on OpReorderer, and
switches AssetAtlas' entry getter methods to using pixelRef pointers,
so it's clear they're the keys.

Change-Id: I3040ce5ff4e178a8364e0fd7ab0876ada7d4de05
diff --git a/libs/hwui/AssetAtlas.h b/libs/hwui/AssetAtlas.h
index f1cd0b4..a037725 100644
--- a/libs/hwui/AssetAtlas.h
+++ b/libs/hwui/AssetAtlas.h
@@ -148,15 +148,15 @@
 
     /**
      * Returns the entry in the atlas associated with the specified
-     * bitmap. If the bitmap is not in the atlas, return NULL.
+     * pixelRef. If the pixelRef is not in the atlas, return NULL.
      */
-    Entry* getEntry(const SkBitmap* bitmap) const;
+    Entry* getEntry(const SkPixelRef* pixelRef) const;
 
     /**
      * Returns the texture for the atlas entry associated with the
-     * specified bitmap. If the bitmap is not in the atlas, return NULL.
+     * specified pixelRef. If the pixelRef is not in the atlas, return NULL.
      */
-    Texture* getEntryTexture(const SkBitmap* bitmap) const;
+    Texture* getEntryTexture(const SkPixelRef* pixelRef) const;
 
 private:
     void createEntries(Caches& caches, int64_t* map, int count);