explicitly bump legacy genID on gpu surface

src/image/SkSurface_Gpu.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 "SkSurface_Gpu.h"
 
 #include "SkCanvas.h"
@@ skipping 17 matching lines @@
 
 GrBackendObject SkSurface_Gpu::onGetTextureHandle(TextureHandleAccess access) {
     GrRenderTarget* rt = fDevice->accessRenderTarget();
     switch (access) {
         case kFlushRead_TextureHandleAccess:
             break;
         case kFlushWrite_TextureHandleAccess:
         case kDiscardWrite_TextureHandleAccess:
             // for now we don't special-case on Discard, but we may in the future.
             this->notifyContentWillChange(kRetain_ContentChangeMode);
+            // legacy: need to dirty the bitmap's genID in our device (curse it)
+            fDevice->fLegacyBitmap.notifyPixelsChanged();
             break;
     }
     rt->prepareForExternalIO();
     return rt->asTexture()->getTextureHandle();
 }
 
 SkCanvas* SkSurface_Gpu::onNewCanvas() {
     SkCanvas::InitFlags flags = SkCanvas::kDefault_InitFlags;
     // When we think this works...
 //    flags |= SkCanvas::kConservativeRasterClip_InitFlag;
@@ skipping 101 matching lines @@
     }
     SkAutoTUnref<SkGpuDevice> device(SkGpuDevice::Create(rt, props,
                                                          SkGpuDevice::kUninit_InitContents));
     if (!device) {
         return NULL;
     }
     return SkNEW_ARGS(SkSurface_Gpu, (device));
 }
 
 #endif