Make Sk2DPathEffect thread safe.

src/effects/Sk2DPathEffect.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "Sk2DPathEffect.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 #include "SkPath.h"
 #include "SkRegion.h"
 #include "SkStrokeRec.h"
 
 Sk2DPathEffect::Sk2DPathEffect(const SkMatrix& mat) : fMatrix(mat) {
-    fMatrixIsInvertible = mat.invert(&fInverse);
+    // Calling invert will set the type mask on both matrices, making them thread safe.
+    fMatrixIsInvertible = fMatrix.invert(&fInverse);
 }
 
 bool Sk2DPathEffect::filterPath(SkPath* dst, const SkPath& src,
                                 SkStrokeRec*, const SkRect*) const {
     if (!fMatrixIsInvertible) {
         return false;
     }
 
     SkPath  tmp;
     SkIRect ir;
@@ skipping 125 matching lines @@
 }
 
 #ifndef SK_IGNORE_TO_STRING
 void SkPath2DPathEffect::toString(SkString* str) const {
     str->appendf("SkPath2DPathEffect: (");
     this->INHERITED::toString(str);
     // TODO: print out path information
     str->appendf(")");
 }
 #endif