Move memoization of multisample specs id to GrRenderTarget

src/gpu/GrRenderTarget.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "GrRenderTarget.h"
 
@@ skipping 87 matching lines @@
     }
     return true;
 }
 
 int GrRenderTargetPriv::numStencilBits() const {
     return fRenderTarget->fStencilAttachment ? fRenderTarget->fStencilAttachment->bits() : 0;
 }
 
 const GrGpu::MultisampleSpecs&
 GrRenderTargetPriv::getMultisampleSpecs(const GrStencilSettings& stencil) const {
-    return fRenderTarget->getGpu()->getMultisampleSpecs(fRenderTarget, stencil);
+    GrGpu* gpu = fRenderTarget->getGpu();
+    if (auto id = fRenderTarget->fMultisampleSpecsID) {
+        SkASSERT(gpu->queryMultisampleSpecs(fRenderTarget, stencil).fUniqueID == id);
+        return gpu->getMultisampleSpecs(id);
+    }
+    const GrGpu::MultisampleSpecs& specs = gpu->queryMultisampleSpecs(fRenderTarget, stencil);
+    fRenderTarget->fMultisampleSpecsID = specs.fUniqueID;
+    return specs;
 }
 
 int GrRenderTargetPriv::maxWindowRectangles() const {
     return (this->flags() & Flags::kWindowRectsSupport) ?
            fRenderTarget->getGpu()->caps()->maxWindowRectangles() : 0;
 }