Add mipmap loading to Vulkan.

src/gpu/GrGpu.h

Index: src/gpu/GrGpu.h
diff --git a/src/gpu/GrGpu.h b/src/gpu/GrGpu.h
index 97ca11ca076019ad9992adac6ebf9b06d7270c62..e38b913a2270c90d8e15908e84545c5da02cac7d 100644
--- a/src/gpu/GrGpu.h
+++ b/src/gpu/GrGpu.h
@@ -512,6 +512,9 @@ protected:
         }
     }
 
+    // Handles cases where a surface will be updated without a call to flushRenderTarget
+    void didWriteToSurface(GrSurface* surface, const SkIRect* bounds, uint32_t mipLevels = 1) const;
+
     Stats                                   fStats;
     SkAutoTDelete<GrPathRendering>          fPathRendering;
     // Subclass must initialize this in its constructor.