skia: Add support for CHROMIUM_image backed textures.

src/gpu/gl/GrGLGpu.h

Index: src/gpu/gl/GrGLGpu.h
diff --git a/src/gpu/gl/GrGLGpu.h b/src/gpu/gl/GrGLGpu.h
index ec93bbfe21492b0b48226065398814eb14ef7a8b..ce2f95ef30e371ed9367426c9884791214fe63a8 100644
--- a/src/gpu/gl/GrGLGpu.h
+++ b/src/gpu/gl/GrGLGpu.h
@@ -159,6 +159,18 @@ private:
     // compatible stencil format, or negative if there is no compatible stencil format.
     int getCompatibleStencilIndex(GrPixelConfig config);
 
+    // If |desc.fTextureStorageAllocator| exists, use that to create the
+    // texture. Otherwise, create the texture directly.
+    // Returns whether the texture is successfully created. On success, the
+    // result is stored in |info|.
+    // The texture is populated with |srcData|, if it exists.
+    // The texture parameters are cached in |initialTexParams|.
+    bool createTextureImpl(const GrSurfaceDesc& desc, GrGLTextureInfo* info,
+                           bool renderTarget, const void* srcData,
+                           GrGLTexture::TexParams* initialTexParams, size_t rowBytes);
+    bool createTextureExternalAllocatorImpl(const GrSurfaceDesc& desc, GrGLTextureInfo* info,
+                                            const void* srcData, size_t rowBytes);
+
     void onClear(GrRenderTarget*, const SkIRect& rect, GrColor color) override;
 
     void onClearStencilClip(GrRenderTarget*, const SkIRect& rect, bool insideClip) override;