Add Gr*Proxy classes

include/gpu/GrContext.h

Index: include/gpu/GrContext.h
diff --git a/include/gpu/GrContext.h b/include/gpu/GrContext.h
index cb407aa5bfa16db1d2c3e7800e0c2c237e7b2804..6f5ca981e5c787f0d26511ee5bfb1358be3443b9 100644
--- a/include/gpu/GrContext.h
+++ b/include/gpu/GrContext.h
@@ -194,16 +194,11 @@ public:
      */
     sk_sp<GrDrawContext> drawContext(sk_sp<GrRenderTarget> rt, const SkSurfaceProps* = nullptr);
 
-    enum BackingFit {
-        kTight_BackingFit,
-        kLoose_BackingFit
-    };
-
     /**
      * Create both a GrRenderTarget and a matching GrDrawContext to wrap it.
      * The created GrRenderTarget will always be budgeted.
      */
-    sk_sp<GrDrawContext> newDrawContext(BackingFit fit, 
+    sk_sp<GrDrawContext> newDrawContext(SkBackingFit fit, 
                                         int width, int height,
                                         GrPixelConfig config,
                                         int sampleCnt = 0,