Rationalize GrContext's Gr*Proxy getter naming

This CL replaces the entry points:

asDeferredSurface
asDeferredTexture
asDeferredRenderTarget

with:

GrSurfaceProxy* asSurfaceProxy
sk_sp<GrSurfaceProxy> asSurfaceProxyRef

GrTextureProxy* asTextureProxy
sk_sp<GrTextureProxy> asTextureProxyRef

GrRenderTargetProxy* asRenderTargetProxy
sk_sp<GrRenderTargetProxy> asRenderTargetProxyRef

Change-Id: I7c2b1ea3d702023ff23019815ca13c9ff6f3b32d
Reviewed-on: https://skia-review.googlesource.com/7741
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
diff --git a/src/effects/SkMorphologyImageFilter.cpp b/src/effects/SkMorphologyImageFilter.cpp
index febde20..75e019b 100644
--- a/src/effects/SkMorphologyImageFilter.cpp
+++ b/src/effects/SkMorphologyImageFilter.cpp
@@ -515,7 +515,7 @@
                                 : SK_ColorTRANSPARENT;
         dstRTContext->clear(&clearRect, clearColor, false);
 
-        srcTexture = sk_ref_sp(dstRTContext->asDeferredTexture());
+        srcTexture = dstRTContext->asTextureProxyRef();
         srcRect = dstRect;
     }
     if (radius.fHeight > 0) {
@@ -530,7 +530,7 @@
                               srcRect, dstRect, radius.fHeight, morphType,
                               Gr1DKernelEffect::kY_Direction);
 
-        srcTexture = sk_ref_sp(dstRTContext->asDeferredTexture());
+        srcTexture = dstRTContext->asTextureProxyRef();
     }
 
     return SkSpecialImage::MakeDeferredFromGpu(context,