skia: Add support for CHROMIUM_image backed textures.

include/core/SkSurface.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkSurface_DEFINED
 #define SkSurface_DEFINED
 
@@ skipping 94 matching lines @@
     /**
      *  Used to wrap a pre-existing 3D API rendering target as a SkSurface. Skia will not assume
      *  ownership of the render target and the client must ensure the render target is valid for the
      *  lifetime of the SkSurface.
      */
     static SkSurface* NewFromBackendRenderTarget(GrContext*, const GrBackendRenderTargetDesc&,
                                                  const SkSurfaceProps*);
 
     /**
      *  Return a new surface whose contents will be drawn to an offscreen
      *  render target, allocated by the surface.

[bsalomon, 2016/02/04 16:27:08]

Put the comment here that the allocator will be reused if additional texture
allocations are made do to SkImage snapshots? I think it will be clearer here
then on GrSurfaceDesc.

[erikchen, 2016/02/04 18:44:07]

Done.

      */
-    static SkSurface* NewRenderTarget(GrContext*, Budgeted, const SkImageInfo&, int sampleCount,
-                                      const SkSurfaceProps* = NULL);
+    static SkSurface* NewRenderTarget(
+            GrContext*, Budgeted, const SkImageInfo&, int sampleCount, const SkSurfaceProps* = NULL,
+            GrTextureStorageAllocator = GrTextureStorageAllocator());
 
     static SkSurface* NewRenderTarget(GrContext* gr, Budgeted b, const SkImageInfo& info) {
-        return NewRenderTarget(gr, b, info, 0, NULL);
+        return NewRenderTarget(gr, b, info, 0);
     }
 
     int width() const { return fWidth; }
     int height() const { return fHeight; }
 
     /**
      *  Returns a unique non-zero, unique value identifying the content of this
      *  surface. Each time the content is changed changed, either by drawing
      *  into this surface, or explicitly calling notifyContentChanged()) this
      *  method will return a new value.
@@ skipping 149 matching lines @@
 private:
     const SkSurfaceProps fProps;
     const int            fWidth;
     const int            fHeight;
     uint32_t             fGenerationID;
 
     typedef SkRefCnt INHERITED;
 };
 
 #endif