Revert "Revert "Remove GrSurfaceDesc member from GrSurface.""

This reverts commit 4b30a96a3e96b7f051e25025f4f17f3c54e04153.

Bug: skia:
Change-Id: I14d5b402c87df8fffbc29f16686fcfa18474fc48
Reviewed-on: https://skia-review.googlesource.com/17408
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/src/gpu/GrRenderTarget.cpp b/src/gpu/GrRenderTarget.cpp
index 61a6f92..8b1fde6 100644
--- a/src/gpu/GrRenderTarget.cpp
+++ b/src/gpu/GrRenderTarget.cpp
@@ -19,11 +19,13 @@
 
 GrRenderTarget::GrRenderTarget(GrGpu* gpu, const GrSurfaceDesc& desc, Flags flags,
                                GrStencilAttachment* stencil)
-    : INHERITED(gpu, desc)
-    , fStencilAttachment(stencil)
-    , fMultisampleSpecsID(0)
-    , fFlags(flags) {
-    SkASSERT(!(fFlags & Flags::kMixedSampled) || fDesc.fSampleCnt > 0);
+        : INHERITED(gpu, desc)
+        , fSampleCnt(desc.fSampleCnt)
+        , fStencilAttachment(stencil)
+        , fMultisampleSpecsID(0)
+        , fFlags(flags) {
+    SkASSERT(desc.fFlags & kRenderTarget_GrSurfaceFlag);
+    SkASSERT(!(fFlags & Flags::kMixedSampled) || fSampleCnt > 0);
     SkASSERT(!(fFlags & Flags::kWindowRectsSupport) || gpu->caps()->maxWindowRectangles() > 0);
     fResolveRect.setLargestInverted();
 }