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/gm/texdata.cpp b/gm/texdata.cpp
index 6b229a3..2921afd 100644
--- a/gm/texdata.cpp
+++ b/gm/texdata.cpp
@@ -118,7 +118,7 @@
         } else {
             vm.reset();
         }
-        paint.addColorTextureProcessor(context, sk_ref_sp(tContext->asDeferredTexture()),
+        paint.addColorTextureProcessor(context, tContext->asTextureProxyRef(),
                                        nullptr, vm);
 
         renderTargetContext->drawRect(clip, GrPaint(paint), GrAA::kNo, vm,