Fixing deferred canvas bug caused by SkTwoPointConicalGradient declaring itself as opaque.

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"
 
@@ skipping 172 matching lines @@
     : SkGradientShaderBase(colors, pos, colorCount, mode, mapper),
     fCenter1(start),
     fCenter2(end),
     fRadius1(startRadius),
     fRadius2(endRadius) {
     // this is degenerate, and should be caught by our caller
     SkASSERT(fCenter1 != fCenter2 || fRadius1 != fRadius2);
     this->init();
 }
 
+bool SkTwoPointConicalGradient::isOpaque() const {
+    // Because areas outside the cone are left untouched, we cannot treat the
+    // shader as opaque even if the gradient itself is opaque.
+    return false;
+}
+
 void SkTwoPointConicalGradient::shadeSpan(int x, int y, SkPMColor* dstCParam,
                                           int count) {
     int toggle = init_dither_toggle(x, y);
 
     SkASSERT(count > 0);
 
     SkPMColor* SK_RESTRICT dstC = dstCParam;
 
     SkMatrix::MapXYProc dstProc = fDstToIndexProc;
 
@@ skipping 548 matching lines @@
     str->appendScalar(fCenter2.fY);
     str->append(") radius2: ");
     str->appendScalar(fRadius2);
     str->append(" ");
 
     this->INHERITED::toString(str);
 
     str->append(")");
 }
 #endif