Swap render target instead of creating a new gpu device for surface copy-on-write

src/gpu/SkGpuDevice.h

 
 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkGpuDevice_DEFINED
 #define SkGpuDevice_DEFINED
@@ skipping 44 matching lines @@
                                                                       kGeneral_Usage,
                                                                       props.pixelGeometry()));
         return static_cast<SkGpuDevice*>(dev);
     }
 
     GrContext* context() const { return fRenderTarget->getContext(); }
 
     // set all pixels to 0
     void clearAll();
 
+    void replaceRenderTarget(bool shouldRetainContent);
+
     GrRenderTarget* accessRenderTarget() SK_OVERRIDE;
 
     SkImageInfo imageInfo() const SK_OVERRIDE {
         return fRenderTarget ? fRenderTarget->surfacePriv().info() : SkImageInfo::MakeUnknown();
     }
 
     const SkSurfaceProps& surfaceProps() const { return fSurfaceProps; }
 
     void drawPaint(const SkDraw&, const SkPaint& paint) SK_OVERRIDE;
     virtual void drawPoints(const SkDraw&, SkCanvas::PointMode mode, size_t count,
@@ skipping 117 matching lines @@
                          const GrTextureParams& params,
                          const SkPaint& paint,
                          SkCanvas::DrawBitmapRectFlags flags,
                          int tileSize,
                          bool bicubic);
 
     bool drawDashLine(const SkPoint pts[2], const SkPaint& paint);
 
     static SkPicture::AccelData::Key ComputeAccelDataKey();
 
+    static GrRenderTarget* CreateRenderTarget(GrContext*, SkSurface::Budgeted, const SkImageInfo&,
+                                              int sampleCount);
+
     typedef SkBaseDevice INHERITED;
 };
 
 #endif