Support GL_SAMPLES queries in null contexts

tools/gpu/gl/debug/GrRenderBufferObj.h

 
 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrRenderBufferObj_DEFINED
 #define GrRenderBufferObj_DEFINED
@@ skipping 12 matching lines @@
 
     void setBound()         { fBound = true; }
     void resetBound()       { fBound = false; }
     bool getBound() const   { return fBound; }
 
     void deleteAction() override {
 
         this->INHERITED::deleteAction();
     }
 
+    void setNumSamples(int numSamples) {
+        GrAlwaysAssert(numSamples > 0);
+        fNumSamples = numSamples;
+    }
+
 protected:
 private:
     bool fBound;           // is this render buffer currently bound via "glBindRenderbuffer"?
 
     typedef GrFBBindableObj INHERITED;
 };
 
 #endif // GrRenderBufferObj_DEFINED