Implement correct clipping for image filters.

src/effects/SkBitmapSource.cpp

 /*
  * Copyright 2012 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmapSource.h"
 #include "SkDevice.h"
 #include "SkCanvas.h"
@@ skipping 65 matching lines @@
 
     *result = device.get()->accessBitmap(false);
     offset->fX = dstIRect.fLeft;
     offset->fY = dstIRect.fTop;
     return true;
 }
 
 void SkBitmapSource::computeFastBounds(const SkRect&, SkRect* dst) const {
     *dst = fDstRect;
 }
+
+bool SkBitmapSource::onFilterBounds(const SkIRect& src, const SkMatrix& ctm,
+                                    SkIRect* dst) const {
+    *dst = src;
+    return true;
+}