Make filters use SkImage instead of SkBitmap

include/core/SkDevice.h

Index: include/core/SkDevice.h
diff --git a/include/core/SkDevice.h b/include/core/SkDevice.h
index 6e02137fb5b817551f7ec2d74ed1fe60a3a888d6..14e583f11a23c8058e1208c5725d263e88bea442 100644
--- a/include/core/SkDevice.h
+++ b/include/core/SkDevice.h
@@ -274,14 +274,14 @@ protected:
 
     /**
      *  Related (but not required) to canHandleImageFilter, this method returns
-     *  true if the device could apply the filter to the src bitmap and return
+     *  true if the device could apply the filter to the src image and return
      *  the result (and updates offset as needed).
      *  If the device does not recognize or support this filter,
      *  it just returns false and leaves result and offset unchanged.
      */
-    virtual bool filterImage(const SkImageFilter*, const SkBitmap&,
+    virtual bool filterImage(const SkImageFilter*, const SkImage*,
                              const SkImageFilter::Context&,
-                             SkBitmap* /*result*/, SkIPoint* /*offset*/) {
+                             SkAutoTUnref<const SkImage>& /*result*/, SkIPoint* /*offset*/) {
         return false;
     }
 
@@ -371,6 +371,8 @@ private:
     friend class SkDeferredDevice;    // for newSurface
     friend class SkNoPixelsBitmapDevice;
 
+    friend class SkSurface;
+    friend class SkSurface_Gpu;
     friend class SkSurface_Raster;
 
     // used to change the backend's pixels (and possibly config/rowbytes)