Revert of Discard atlas after every MultiPictureDraw::draw

src/gpu/GrLayerCache.h

Index: src/gpu/GrLayerCache.h
diff --git a/src/gpu/GrLayerCache.h b/src/gpu/GrLayerCache.h
index 14967b7049d8f78b709ea91454478fab03bf4bef..58887d6405c9e6d820c23dba96a498f4ab4a9dc3 100644
--- a/src/gpu/GrLayerCache.h
+++ b/src/gpu/GrLayerCache.h
@@ -17,9 +17,6 @@
 #include "SkTDynamicHash.h"
 
 class SkPicture;
-
-// Set to 0 to disable caching of hoisted layers
-#define GR_CACHE_HOISTED_LAYERS 0
 
 // The layer cache listens for these messages to purge picture-related resources.
 struct GrPictureDeletedMessage {
@@ -252,10 +249,6 @@
         return width <= kPlotWidth && height <= kPlotHeight;
     }
 
-#if !GR_CACHE_HOISTED_LAYERS
-    void purgeAll();
-#endif
-
 private:
     static const int kAtlasTextureWidth = 1024;
     static const int kAtlasTextureHeight = 1024;
@@ -298,6 +291,8 @@
                                const SkIRect& bounds, const SkMatrix& ctm, 
                                const SkPaint* paint);
 
+    void purgeAll();
+
     // Remove all the layers (and unlock any resources) associated with 'pictureID'
     void purge(uint32_t pictureID);