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

src/gpu/SkGpuDevice.h

Index: src/gpu/SkGpuDevice.h
diff --git a/src/gpu/SkGpuDevice.h b/src/gpu/SkGpuDevice.h
index 6cbf628e58b90724608af7dedc751fe5b60c2c03..9eddc41a21521153902ac8b27037b4fc56f2c37d 100644
--- a/src/gpu/SkGpuDevice.h
+++ b/src/gpu/SkGpuDevice.h
@@ -50,6 +50,10 @@ public:
 
     virtual ~SkGpuDevice();
 
+    /** Creates a render targetthat can be used as the render target of the device. */
+    static GrRenderTarget* CreateRenderTarget(GrContext* context, SkSurface::Budgeted budgeted,

[bsalomon, 2015/02/18 14:29:36]

Is it possible to just infer the parameters for the new RT from the old RT?
Maybe by making this method non-static? Or maybe have

GrRenderTarget* replaceRenderTarget(bool copyOldToNew);

that creates the new one (using budgeted status of the old one) and returns the
old one?

[Kimmo Kinnunen, 2015/02/18 14:42:54]

Yeah, this is just a refactoring. I did not hone it, since the problem you
address may be going away (the can be seen as "inferred") in:
https://chromiumcodereview.appspot.com/926843003/

+                                              const SkImageInfo& info, int sampleCount);
+
     SkGpuDevice* cloneDevice(const SkSurfaceProps& props) {
         SkBaseDevice* dev = this->onCreateCompatibleDevice(CreateInfo(this->imageInfo(),
                                                                       kGeneral_Usage,
@@ -62,6 +66,8 @@ public:
     // set all pixels to 0
     void clearAll();
 
+    void swapRenderTarget(GrRenderTarget* newTarget);
+
     GrRenderTarget* accessRenderTarget() SK_OVERRIDE;
 
     SkImageInfo imageInfo() const SK_OVERRIDE {