Move GrContext::makeDrawContext to new GrContextPriv object

src/gpu/GrContextPriv.h

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrContextPriv_DEFINED
+#define GrContextPriv_DEFINED
+
+#include "GrContext.h"
+
+/** Class that adds methods to GrContext that are only intended for use internal to Skia.
+    This class is purely a privileged window into GrContext. It should never have additional
+    data members or virtual methods. */
+class GrContextPriv {
+public:
+    // Create a drawContext that wraps an existing renderTarget
+    sk_sp<GrDrawContext> makeWrappedDrawContext(sk_sp<GrRenderTarget> rt,
+                                                sk_sp<SkColorSpace> colorSpace,
+                                                const SkSurfaceProps* = nullptr);
+
+    sk_sp<GrDrawContext> makeBackendTextureDrawContext(const GrBackendTextureDesc& desc,
+                                                       sk_sp<SkColorSpace> colorSpace,
+                                                       const SkSurfaceProps* = nullptr,
+                                                       GrWrapOwnership = kBorrow_GrWrapOwnership);
+
+    sk_sp<GrDrawContext> makeBackendRenderTargetDrawContext(const GrBackendRenderTargetDesc& desc,
+                                                            sk_sp<SkColorSpace> colorSpace,
+                                                            const SkSurfaceProps* = nullptr);
+
+    sk_sp<GrDrawContext> makeBackendTextureAsRenderTargetDrawContext(
+                                                                 const GrBackendTextureDesc& desc,
+                                                                 sk_sp<SkColorSpace> colorSpace,
+                                                                 const SkSurfaceProps* = nullptr);
+
+private:
+    explicit GrContextPriv(GrContext* context) : fContext(context) {}
+    GrContextPriv(const GrContextPriv&) {} // unimpl
+    GrContextPriv& operator=(const GrContextPriv&); // unimpl
+
+    // No taking addresses of this type.
+    const GrContextPriv* operator&() const;
+    GrContextPriv* operator&();
+
+    GrContext* fContext;
+
+    friend class GrContext; // to construct/copy this type.
+};
+
+inline GrContextPriv GrContext::contextPriv() { return GrContextPriv(this); }
+
+inline const GrContextPriv GrContext::contextPriv () const {
+    return GrContextPriv(const_cast<GrContext*>(this));
+}
+
+#endif