Simplify flattening to just write enough to call the factory

include/core/SkImageFilter.h

Index: include/core/SkImageFilter.h
diff --git a/include/core/SkImageFilter.h b/include/core/SkImageFilter.h
index cd34ba3f91bd55664c05ce46a6e268003e22ba8f..3fd046e7daaa70bfc8c42adcac55d01e93d21385 100644
--- a/include/core/SkImageFilter.h
+++ b/include/core/SkImageFilter.h
@@ -205,12 +205,21 @@ protected:
         Common() {}
         ~Common();
 
+        /**
+         *  Attempt to unflatten the cropRect and the expected number of input filters.
+         *  If any number of input filters is valid, pass -1.
+         *  If this fails (i.e. corrupt buffer or contents) then return false and common will
+         *  be left uninitialized.
+         *  If this returns true, then inputCount() is the number of found input filters, each
+         *  of which may be NULL or a valid imagefilter.
+         */
         bool unflatten(SkReadBuffer&, int expectedInputs = -1);
 
-        CropRect        cropRect() const { return fCropRect; }
+        const CropRect& cropRect() const { return fCropRect; }
         int             inputCount() const { return fInputs.count(); }
         SkImageFilter** inputs() const { return fInputs.get(); }
-
+        SkImageFilter*  inputAt(int index) const { return fInputs[index]; }
+    
         // If the caller wants a copy of the inputs, call this and it will transfer ownership
         // of the unflattened input filters to the caller. This is just a short-cut for copying
         // the inputs, calling ref() on each, and then waiting for Common's destructor to call
@@ -238,7 +247,7 @@ protected:
      */
     explicit SkImageFilter(int inputCount, SkReadBuffer& rb);
 
-    virtual void flatten(SkWriteBuffer& wb) const SK_OVERRIDE;
+    void flattenCommon(SkWriteBuffer&) const;
 
     /**
      *  This is the virtual which should be overridden by the derived class