Make SkGpuDevice constructors private.

R=robertphillips@google.com

Author: bsalomon@google.com

Review URL: https://codereview.chromium.org/517033002
diff --git a/debugger/QT/SkGLWidget.cpp b/debugger/QT/SkGLWidget.cpp
index 019654f..602dc24 100644
--- a/debugger/QT/SkGLWidget.cpp
+++ b/debugger/QT/SkGLWidget.cpp
@@ -47,7 +47,7 @@
     GrBackendRenderTargetDesc desc = this->getDesc(this->width(), this->height());
     desc.fOrigin = kBottomLeft_GrSurfaceOrigin;
     GrRenderTarget* curRenderTarget = fCurContext->wrapBackendRenderTarget(desc);
-    fGpuDevice = new SkGpuDevice(fCurContext, curRenderTarget);
+    fGpuDevice = SkGpuDevice::Create(curRenderTarget);
     fCanvas = new SkCanvas(fGpuDevice);
     curRenderTarget->unref();
 }
@@ -65,7 +65,7 @@
         GrRenderTarget* curRenderTarget = fCurContext->wrapBackendRenderTarget(desc);
         SkSafeUnref(fGpuDevice);
         SkSafeUnref(fCanvas);
-        fGpuDevice = new SkGpuDevice(fCurContext, curRenderTarget);
+        fGpuDevice = SkGpuDevice::Create(curRenderTarget);
         fCanvas = new SkCanvas(fGpuDevice);
     }
     fDebugger->resize(w, h);