Harden degenerate gradient context handling

src/effects/gradients/SkTwoPointConicalGradient.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkTwoPointConicalGradient.h"
 
 struct TwoPtRadialContext {
@@ skipping 198 matching lines @@
     // TODO(junov): Compute whether the cone fills the plane crbug.com/222380
     return false;
 }
 
 size_t SkTwoPointConicalGradient::onContextSize(const ContextRec&) const {
     return sizeof(TwoPointConicalGradientContext);
 }
 
 SkShader::Context* SkTwoPointConicalGradient::onCreateContext(const ContextRec& rec,
                                                               void* storage) const {
-    return new (storage) TwoPointConicalGradientContext(*this, rec);
+    return CheckedCreateContext<TwoPointConicalGradientContext>(storage, *this, rec);
 }
 
 SkTwoPointConicalGradient::TwoPointConicalGradientContext::TwoPointConicalGradientContext(
         const SkTwoPointConicalGradient& shader, const ContextRec& rec)
     : INHERITED(shader, rec)
 {
     // in general, we might discard based on computed-radius, so clear
     // this flag (todo: sometimes we can detect that we never discard...)
     fFlags &= ~kOpaqueAlpha_Flag;
 }
@@ skipping 159 matching lines @@
     str->appendScalar(fCenter2.fY);
     str->append(") radius2: ");
     str->appendScalar(fRadius2);
     str->append(" ");
 
     this->INHERITED::toString(str);
 
     str->append(")");
 }
 #endif