Port most uses of SkOnce to SkLazyPtr.

src/core/SkMatrix.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 "SkMatrix.h"
 #include "SkFloatBits.h"
-#include "SkOnce.h"
+#include "SkLazyPtr.h"
 #include "SkString.h"
 
 // In a few places, we performed the following
 //      a * b + c * d + e
 // as
 //      a * b + (c * d + e)
 //
 // sdot and scross are indended to capture these compound operations into a
 // function, with an eye toward considering upscaling the intermediates to
 // doubles for more precision (as we do in concat and invert).
@@ skipping 1530 matching lines @@
         return factor;
     } else {
         return -1;
     }
 }
 
 bool SkMatrix::getMinMaxScales(SkScalar scaleFactors[2]) const {
     return get_scale_factor<kBoth_MinMaxOrBoth>(this->getType(), fMat, scaleFactors);
 }
 
-static void reset_identity_matrix(SkMatrix* identity) {
-    identity->reset();
+namespace {
+
+SkMatrix* create_identity() {
+    SkMatrix* m = SkNEW(SkMatrix);
+    m->reset();
+    return m;
 }
 
+SkMatrix* create_invalid() {
+    SkMatrix* m = SkNEW(SkMatrix);
+    m->setAll(SK_ScalarMax, SK_ScalarMax, SK_ScalarMax,
+              SK_ScalarMax, SK_ScalarMax, SK_ScalarMax,
+              SK_ScalarMax, SK_ScalarMax, SK_ScalarMax);
+    m->getType();  // Force the type to be computed.
+    return m;
+}
+
+}  // namespace
+
 const SkMatrix& SkMatrix::I() {
-    // If you can use C++11 now, you might consider replacing this with a constexpr constructor.
-    static SkMatrix gIdentity;
-    SK_DECLARE_STATIC_ONCE(once);
-    SkOnce(&once, reset_identity_matrix, &gIdentity);
-    return gIdentity;
+    SK_DECLARE_STATIC_LAZY_PTR(SkMatrix, identity, create_identity);
+    return *identity.get();
 }
 
 const SkMatrix& SkMatrix::InvalidMatrix() {
-    static SkMatrix gInvalid;
-    static bool gOnce;
-    if (!gOnce) {
-        gInvalid.setAll(SK_ScalarMax, SK_ScalarMax, SK_ScalarMax,
-                        SK_ScalarMax, SK_ScalarMax, SK_ScalarMax,
-                        SK_ScalarMax, SK_ScalarMax, SK_ScalarMax);
-        gInvalid.getType(); // force the type to be computed
-        gOnce = true;
-    }
-    return gInvalid;
+    SK_DECLARE_STATIC_LAZY_PTR(SkMatrix, invalid, create_invalid);
+    return *invalid.get();
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 size_t SkMatrix::writeToMemory(void* buffer) const {
     // TODO write less for simple matrices
     static const size_t sizeInMemory = 9 * sizeof(SkScalar);
     if (buffer) {
         memcpy(buffer, fMat, sizeInMemory);
     }
@@ skipping 174 matching lines @@
         rotation1->fX = cos1;
         rotation1->fY = sin1;
     }
     if (NULL != rotation2) {
         rotation2->fX = cos2;
         rotation2->fY = sin2;
     }
 
     return true;
 }