Add Gr*Proxy classes

include/private/GrTextureProxy.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 GrTextureProxy_DEFINED
+#define GrTextureProxy_DEFINED
+
+#include "GrSurfaceProxy.h"
+#include "GrTexture.h"
+
+class GrTextureProvider;
+
+// This class delays the acquisition of textures until they are actually required
+class GrTextureProxy : public GrSurfaceProxy {
+public:
+    // TODO: need to refine ownership semantics of 'srcData' if we're in completely
+    // deferred mode
+    static sk_sp<GrTextureProxy> Make(const GrSurfaceDesc&, SkBackingFit, SkBudgeted,
+                                      const void* srcData = nullptr, size_t rowBytes = 0);
+    static sk_sp<GrTextureProxy> Make(sk_sp<GrTexture>);
+
+    // TODO: add asRenderTargetProxy variants
+    GrTextureProxy* asTextureProxy() override { return this; }
+    const GrTextureProxy* asTextureProxy() const override { return this; }
+
+    // Actually instantiate the backing texture, if necessary
+    GrTexture* instantiate(GrTextureProvider* texProvider);
+
+private:
+    GrTextureProxy(const GrSurfaceDesc& desc, SkBackingFit fit, SkBudgeted budgeted,
+                   const void* /*srcData*/, size_t /*rowBytes*/)
+        : INHERITED(desc, fit, budgeted) {
+        // TODO: Handle 'srcData' here
+    }
+
+    // Wrapped version
+    GrTextureProxy(sk_sp<GrTexture> tex);
+
+    // For wrapped textures we store it here.
+    // For deferred proxies we will fill this in when we need to instantiate the deferred resource
+    sk_sp<GrTexture> fTexture;
+
+    typedef GrSurfaceProxy INHERITED;
+};
+
+#endif