Use SkPathRef gen id for SkPath::getGenerationID

include/core/SkPath.h

Index: include/core/SkPath.h
diff --git a/include/core/SkPath.h b/include/core/SkPath.h
index a6674d9afb4e65cc024ee8a155d5f4f4b4869bfe..9b5dc4bf65f11c33358188042cf45f9bdba98052 100644
--- a/include/core/SkPath.h
+++ b/include/core/SkPath.h
@@ -16,14 +16,6 @@
 #include "SkTDArray.h"
 #include "SkRefCnt.h"
 
-#ifdef SK_BUILD_FOR_ANDROID
-#define GEN_ID_INC              fGenerationID++
-#define GEN_ID_PTR_INC(ptr)     (ptr)->fGenerationID++
-#else
-#define GEN_ID_INC
-#define GEN_ID_PTR_INC(ptr)
-#endif
-
 class SkReader32;
 class SkWriter32;
 class SkAutoPathBoundsUpdate;
@@ -40,10 +32,10 @@ public:
     SK_DECLARE_INST_COUNT_ROOT(SkPath);
 
     SkPath();
-    SkPath(const SkPath&);  // Copies fGenerationID on Android.
+    SkPath(const SkPath&);
     ~SkPath();
 
-    SkPath& operator=(const SkPath&);  // Increments fGenerationID on Android.
+    SkPath& operator=(const SkPath&);
     friend  SK_API bool operator==(const SkPath&, const SkPath&);
     friend bool operator!=(const SkPath& a, const SkPath& b) {
         return !(a == b);
@@ -80,7 +72,6 @@ public:
     */
     void setFillType(FillType ft) {
         fFillType = SkToU8(ft);
-        GEN_ID_INC;
     }
 
     /** Returns true if the filltype is one of the Inverse variants */
@@ -92,7 +83,6 @@ public:
      */
     void toggleInverseFillType() {
         fFillType ^= 2;
-        GEN_ID_INC;
      }
 
     enum Convexity {
@@ -914,16 +904,25 @@ public:
      *  If buffer is NULL, it still returns the number of bytes.
      */
     uint32_t writeToMemory(void* buffer) const;
+
     /**
      *  Initialized the region from the buffer, returning the number
      *  of bytes actually read.
      */
     uint32_t readFromMemory(const void* buffer);
 
-#ifdef SK_BUILD_FOR_ANDROID
+    /** Returns a non-zero, globally unique value corresponding to the set of verbs
+        and points in the path (but not the fill type [except on Android skbug.com/1762]).
+        Each time the path is modified, a different generation ID will be returned. 
+    */
     uint32_t getGenerationID() const;
+
+#ifdef SK_BUILD_FOR_ANDROID
+    static const int kPathRefGenIDBitCnt = 30; // leave room for the fill type (skbug.com/1762)
     const SkPath* getSourcePath() const;
     void setSourcePath(const SkPath* path);
+#else
+    static const int kPathRefGenIDBitCnt = 32;
 #endif
 
     SkDEBUGCODE(void validate() const;)
@@ -953,7 +952,6 @@ private:
     mutable uint8_t     fDirection;
     mutable SkBool8     fIsOval;
 #ifdef SK_BUILD_FOR_ANDROID
-    uint32_t            fGenerationID;
     const SkPath*       fSourcePath;
 #endif