images with offset bitmap don't share genid

src/image/SkImage_Raster.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkImage_Base.h"
 #include "SkBitmap.h"
 #include "SkCanvas.h"
@@ skipping 64 matching lines @@
 
     // exposed for SkSurface_Raster via SkNewImageFromPixelRef
     SkImage_Raster(const SkImageInfo&, SkPixelRef*, const SkIPoint& origin, size_t rowBytes);
 
     SkPixelRef* getPixelRef() const { return fBitmap.pixelRef(); }
 
     bool isOpaque() const override;
     bool onAsLegacyBitmap(SkBitmap*, LegacyBitmapMode) const override;
 
     SkImage_Raster(const SkBitmap& bm)
-        : INHERITED(bm.width(), bm.height(), bm.getGenerationID())
+        : INHERITED(bm.width(), bm.height(),
+                    bm.pixelRefOrigin().isZero()
+                    ? bm.getGenerationID()
+                    : (uint32_t)kNeedNewImageUniqueID)
         , fBitmap(bm)
     {
         if (bm.pixelRef()->isPreLocked()) {
             // we only preemptively lock if there is no chance of triggering something expensive
             // like a lazy decode or imagegenerator. PreLocked means it is flat pixels already.
             fBitmap.lockPixels();
         }
         SkASSERT(fBitmap.isImmutable());
     }
 
@@ skipping 182 matching lines @@
         // pixelref since the caller might call setImmutable() themselves
         // (thus changing our state).
         if (fBitmap.isImmutable()) {
             bitmap->setInfo(fBitmap.info(), fBitmap.rowBytes());
             bitmap->setPixelRef(fBitmap.pixelRef(), fBitmap.pixelRefOrigin());
             return true;
         }
     }
     return this->INHERITED::onAsLegacyBitmap(bitmap, mode);
 }