use Make instead of Create to return a shared shader

Partially updated call sites. Undefine the flag in SkSHader.h to convert the remaining sites.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1772463002

Review URL: https://codereview.chromium.org/1772463002
diff --git a/samplecode/SampleBigGradient.cpp b/samplecode/SampleBigGradient.cpp
index 0fa7969..8ae0990 100644
--- a/samplecode/SampleBigGradient.cpp
+++ b/samplecode/SampleBigGradient.cpp
@@ -1,20 +1,19 @@
-
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
+
 #include "SampleCode.h"
 #include "SkView.h"
 #include "SkCanvas.h"
 #include "SkGradientShader.h"
 
-static SkShader* make_grad(SkScalar w, SkScalar h) {
+static sk_sp<SkShader> make_grad(SkScalar w, SkScalar h) {
     SkColor colors[] = { 0xFF000000, 0xFF333333 };
     SkPoint pts[] = { { 0, 0 }, { w, h } };
-    return SkGradientShader::CreateLinear(pts, colors, nullptr, 2,
-                                          SkShader::kClamp_TileMode);
+    return SkGradientShader::MakeLinear(pts, colors, nullptr, 2, SkShader::kClamp_TileMode);
 }
 
 class BigGradientView : public SampleView {
@@ -22,8 +21,7 @@
     BigGradientView() {}
 
 protected:
-    // overrides from SkEventSink
-    virtual bool onQuery(SkEvent* evt) {
+    bool onQuery(SkEvent* evt) override {
         if (SampleCode::TitleQ(*evt)) {
             SampleCode::TitleR(evt, "BigGradient");
             return true;
@@ -31,11 +29,11 @@
         return this->INHERITED::onQuery(evt);
     }
 
-    virtual void onDrawContent(SkCanvas* canvas) {
+    void onDrawContent(SkCanvas* canvas) override {
         SkRect r;
         r.set(0, 0, this->width(), this->height());
         SkPaint p;
-        p.setShader(make_grad(this->width(), this->height()))->unref();
+        p.setShader(make_grad(this->width(), this->height()));
         canvas->drawRect(r, p);
     }