Convert SkPicture's generation ID to a unique ID

src/gpu/GrLayerCache.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrLayerCache_DEFINED
 #define GrLayerCache_DEFINED
 
@@ skipping 29 matching lines @@
 
 private:
     GrPlot*   fPlot;
     GrIRect16 fBounds;  // only valid is fPlot != NULL
 };
 
 // A GrAtlasedLayer encapsulates the atlasing information for a single saveLayer.
 // It is roughly equivalent to a GrGlyph in the font caching system
 class GrAtlasedLayer {
 public:
-    GrAtlasedLayer() : fPictureID(SkPicture::kInvalidGenID) { }
+    GrAtlasedLayer() : fPictureID(SK_InvalidGenID) { }
 
     uint32_t pictureID() const { return fPictureID; }
     int layerID() const { return fLayerID; }
 
     void init(uint32_t pictureID, int layerID) {
         fPictureID = pictureID;
         fLayerID   = layerID;
     }
 
 private:
@@ skipping 23 matching lines @@
     class PictureLayerKey;
     GrTHashTable<GrAtlasedLayer, PictureLayerKey, 7> fLayerHash;
     GrTAllocPool<GrAtlasedLayer> fLayerPool;
 
     void init();
     GrAtlasedLayer* createLayer(SkPicture* picture, int id);
 
 };
 
 #endif