Revert of Implement SkImageFilter::Cache with SkResourceCache.

include/core/SkImageFilter.h

Index: include/core/SkImageFilter.h
diff --git a/include/core/SkImageFilter.h b/include/core/SkImageFilter.h
index 948415993631b1606c187938e6f31edcfc5c03f3..1ca1c01c08b2b4c49827358b0d52c2fa8a2dd35d 100644
--- a/include/core/SkImageFilter.h
+++ b/include/core/SkImageFilter.h
@@ -42,6 +42,7 @@
         static Cache* Get();
         virtual bool get(const Key& key, SkBitmap* result, SkIPoint* offset) const = 0;
         virtual void set(const Key& key, const SkBitmap& result, const SkIPoint& offset) = 0;
+        virtual void purge() {}
     };
 
     class Context {
@@ -374,6 +375,9 @@
     virtual bool affectsTransparentBlack() const;
 
 private:
+    friend class SkGraphics;
+    static void PurgeCache();
+
     bool usesSrcInput() const { return fUsesSrcInput; }
 
     typedef SkFlattenable INHERITED;