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

src/gpu/GrLayerAtlas.h

Index: src/gpu/GrLayerAtlas.h
diff --git a/src/gpu/GrLayerAtlas.h b/src/gpu/GrLayerAtlas.h
index ae08e4527ba6738cba02b2a73986028d2a3d832d..e84667b5ea02cec6b8ca4e2cb9b75c84a896da24 100644
--- a/src/gpu/GrLayerAtlas.h
+++ b/src/gpu/GrLayerAtlas.h
@@ -9,15 +9,13 @@
 #ifndef GrLayerAtlas_DEFINED
 #define GrLayerAtlas_DEFINED
 
-#include "GrTypes.h"
+#include "GrTexture.h"
 
 #include "SkPoint.h"
-#include "SkSize.h"
 #include "SkTDArray.h"
 #include "SkTInternalLList.h"
 
 class GrLayerAtlas;
-class GrTexture;
 class GrTextureProvider;
 class GrRectanizer;
 
@@ -109,10 +107,23 @@ public:
     // nullptr is returned if there is no more space in the atlas.
     Plot* addToAtlas(ClientPlotUsage*, int width, int height, SkIPoint16* loc);
 
+    GrTexture* getTextureOrNull() const {
+        return fTexture;
+    }
+
     GrTexture* getTexture() const {
+        SkASSERT(fTexture);
         return fTexture;
     }
 
+    bool reattachBackingTexture();
+
+    void detachBackingTexture() {
+        fTexture.reset(nullptr);
+    }
+
+    void resetPlots();
+
     enum IterOrder {
         kLRUFirst_IterOrder,
         kMRUFirst_IterOrder
@@ -127,12 +138,14 @@ public:
     }
 
 private:
+    void createBackingTexture();
+
     void makeMRU(Plot* plot);
 
     GrTextureProvider* fTexProvider;
     GrPixelConfig      fPixelConfig;
     GrSurfaceFlags     fFlags;
-    GrTexture*         fTexture;
+    SkAutoTUnref<GrTexture> fTexture;
 
     SkISize            fBackingTextureSize;