Change SkMatrix::fixedStepInX to return SkVector rather than SkFixed.

src/effects/gradients/SkLinearGradient.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 "SkLinearGradient.h"
 
 static const float kInv255Float = 1.0f / 255;
@@ skipping 269 matching lines @@
     TileProc            proc = linearGradient.fTileProc;
     const SkPMColor* SK_RESTRICT cache = fCache->getCache32();
     int                 toggle = init_dither_toggle(x, y);
 
     if (fDstToIndexClass != kPerspective_MatrixClass) {
         dstProc(fDstToIndex, SkIntToScalar(x) + SK_ScalarHalf,
                              SkIntToScalar(y) + SK_ScalarHalf, &srcPt);
         SkGradFixed dx, fx = SkScalarToGradFixed(srcPt.fX);
 
         if (fDstToIndexClass == kFixedStepInX_MatrixClass) {
-            SkFixed dxStorage[1];
-            (void)fDstToIndex.fixedStepInX(SkIntToScalar(y), dxStorage, nullptr);
+            const auto step = fDstToIndex.fixedStepInX(SkIntToScalar(y));
             // todo: do we need a real/high-precision value for dx here?
-            dx = SkFixedToGradFixed(dxStorage[0]);
+            dx = SkScalarToGradFixed(step.fX);
         } else {
             SkASSERT(fDstToIndexClass == kLinear_MatrixClass);
             dx = SkScalarToGradFixed(fDstToIndex.getScaleX());
         }
 
         LinearShadeProc shadeProc = shadeSpan_linear_repeat;
         if (0 == dx) {
             shadeProc = shadeSpan_linear_vertical_lerp;
         } else if (SkShader::kClamp_TileMode == linearGradient.fTileMode) {
             shadeProc = shadeSpan_linear_clamp;
@@ skipping 436 matching lines @@
             this->shade4_dx_clamp<false, true>(dstC, count, fx, dx, invDx, dither);
         }
     } else {
         if (fApplyAlphaAfterInterp) {
             this->shade4_dx_clamp<true, false>(dstC, count, fx, dx, invDx, dither);
         } else {
             this->shade4_dx_clamp<false, false>(dstC, count, fx, dx, invDx, dither);
         }
     }
 }
-