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/SampleAARects.cpp b/samplecode/SampleAARects.cpp
index f552df6..d0c1115 100644
--- a/samplecode/SampleAARects.cpp
+++ b/samplecode/SampleAARects.cpp
@@ -62,10 +62,8 @@
         SkPaint bluePaint;
         bluePaint.setARGB(0xff, 0x0, 0x0, 0xff);
         SkPaint bmpPaint;
-        SkShader* bmpShader = SkShader::CreateBitmapShader(fBitmap, SkShader::kRepeat_TileMode, SkShader::kRepeat_TileMode);
-        bmpPaint.setShader(bmpShader);
-        bmpShader->unref();
-
+        bmpPaint.setShader(SkShader::MakeBitmapShader(fBitmap, SkShader::kRepeat_TileMode,
+                                                      SkShader::kRepeat_TileMode));
         bluePaint.setStrokeWidth(3);
         bmpPaint.setStrokeWidth(3);