Initial error handling code

include/effects/SkDisplacementMapEffect.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkDisplacementMapEffect_DEFINED
 #define SkDisplacementMapEffect_DEFINED
 
 #include "SkImageFilter.h"
 #include "SkBitmap.h"
 
 class SK_API SkDisplacementMapEffect : public SkImageFilter {
+    typedef SkImageFilter INHERITED;
+
 public:
     enum ChannelSelectorType {
         kUnknown_ChannelSelectorType,
         kR_ChannelSelectorType,
         kG_ChannelSelectorType,
         kB_ChannelSelectorType,
         kA_ChannelSelectorType,
         kKeyBits = 3 // Max value is 4, so 3 bits are required at most
     };
 
@@ skipping 18 matching lines @@
 #endif
 
 protected:
     explicit SkDisplacementMapEffect(SkFlattenableReadBuffer& buffer);
     virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE;
 
 private:
     ChannelSelectorType fXChannelSelector;
     ChannelSelectorType fYChannelSelector;
     SkScalar fScale;
-    typedef SkImageFilter INHERITED;
     SkImageFilter* getDisplacementInput() { return getInput(0); }
     SkImageFilter* getColorInput() { return getInput(1); }
 };
 
 #endif