Update Layer Hoisting to store its atlas texture in the resource cache

src/core/SkMultiPictureDraw.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 // Need to include something before #if SK_SUPPORT_GPU so that the Android
 // framework build, which gets its defines from SkTypes rather than a makefile,
 // has the definition before checking it.
@@ skipping 98 matching lines @@
 
 #if !defined(SK_IGNORE_GPU_LAYER_HOISTING) && SK_SUPPORT_GPU
     GrContext* context = fGPUDrawData[0].fCanvas->getGrContext();
     SkASSERT(context);
 
     // Start by collecting all the layers that are going to be atlased and render
     // them (if necessary). Hoisting the free floating layers is deferred until
     // drawing the canvas that requires them.
     SkTDArray<GrHoistedLayer> atlasedNeedRendering, atlasedRecycled;
 
+    GrLayerHoister::Begin(context);
+
     for (int i = 0; i < count; ++i) {
         const DrawData& data = fGPUDrawData[i];
         // we only expect 1 context for all the canvases
         SkASSERT(data.fCanvas->getGrContext() == context);
 
         if (!data.fPaint) {
             SkRect clipBounds;
             if (!data.fCanvas->getClipBounds(&clipBounds)) {
                 continue;
             }
@@ skipping 63 matching lines @@
             canvas->drawPicture(picture, &data.fMatrix, data.fPaint);
         }
         if (flush) {
             canvas->flush();
         }
     }
 
 #if !defined(SK_IGNORE_GPU_LAYER_HOISTING) && SK_SUPPORT_GPU
     GrLayerHoister::UnlockLayers(context, atlasedNeedRendering);
     GrLayerHoister::UnlockLayers(context, atlasedRecycled);
-#if !GR_CACHE_HOISTED_LAYERS
-    GrLayerHoister::PurgeCache(context);
-#endif
+    GrLayerHoister::End(context);
 #endif
 }