Invalidate GrTexture mipmap on content change notification

include/core/SkPixelRef.h

 /*
  * Copyright 2008 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.
  */
 
 #ifndef SkPixelRef_DEFINED
 #define SkPixelRef_DEFINED
 
@@ skipping 295 matching lines @@
      *  For pixelrefs that don't have access to their raw pixels, they may be
      *  able to make a copy of them (e.g. if the pixels are on the GPU).
      *
      *  The base class implementation returns false;
      */
     virtual bool onReadPixels(SkBitmap* dst, const SkIRect* subsetOrNull);
 
     // default impl returns NULL.
     virtual SkData* onRefEncodedData();
 
+    // default impl does nothing.
+    virtual void onNotifyPixelsChanged();
+
     // default impl returns false.
     virtual bool onGetYUV8Planes(SkISize sizes[3], void* planes[3], size_t rowBytes[3],
                                  SkYUVColorSpace* colorSpace);
 
     /**
      *  Returns the size (in bytes) of the internally allocated memory.
      *  This should be implemented in all serializable SkPixelRef derived classes.
      *  SkBitmap::fPixelRefOffset + SkBitmap::getSafeSize() should never overflow this value,
      *  otherwise the rendering code may attempt to read memory out of bounds.
      *
@@ skipping 62 matching lines @@
     /**
      *  Allocate a new pixelref matching the specified ImageInfo, allocating
      *  the memory for the pixels. If the ImageInfo requires a ColorTable,
      *  the pixelref will ref() the colortable.
      *  On failure return NULL.
      */
     virtual SkPixelRef* create(const SkImageInfo&, size_t rowBytes, SkColorTable*) = 0;
 };
 
 #endif