Add an Android-framework-only stable ID to SkPixelRef.

include/core/SkPixelRef.h

Index: include/core/SkPixelRef.h
diff --git a/include/core/SkPixelRef.h b/include/core/SkPixelRef.h
index 6f0421e3c4f36dbf11d440b75225ed65a15a1c04..d8c8d565c2ba65d7c28236e119867ff38ba9fa07 100644
--- a/include/core/SkPixelRef.h
+++ b/include/core/SkPixelRef.h
@@ -127,6 +127,17 @@ public:
     */
     uint32_t getGenerationID() const;
 
+#ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
+    /** Returns a non-zero, unique value corresponding to this SkPixelRef,
+        which is unchanged when the pixels are changed and even when this
+        object is deleted.
+
+        Can be used as a key which must remain unique across changes and
+        deletions.
+     */
+    uint32_t getStableID() const { return fStableID; }

[reed1, 2014/11/25 15:54:06]

bikeshed: getStructureID or some name that refers to the part that is being ID'd
?

+#endif
+
     /**
      *  Call this if you have changed the contents of the pixels. This will in-
      *  turn cause a different generation ID value to be returned from
@@ -358,6 +369,9 @@ private:
 
     mutable SkTRacy<uint32_t> fGenerationID;
     mutable SkTRacy<bool>     fUniqueGenerationID;
+#ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
+    const uint32_t fStableID;
+#endif
 
     SkTDArray<GenIDChangeListener*> fGenIDChangeListeners;  // pointers are owned