Factor code to rotate a canvas about a point.

gm/fontscaler.cpp

Index: gm/fontscaler.cpp
diff --git a/gm/fontscaler.cpp b/gm/fontscaler.cpp
index 69cf346c4d2826d1c69825a4b3b5158f798f125b..fb49f61570c95ec47c6e9cc66f5b275e43f67bdb 100644
--- a/gm/fontscaler.cpp
+++ b/gm/fontscaler.cpp
@@ -6,6 +6,7 @@
  */
 #include "gm.h"
 #include "SkTypeface.h"
+#include "sk_tool_utils.h"
 
 namespace skiagm {
 
@@ -15,9 +16,6 @@ public:
         this->setBGColor(0xFFFFFFFF);
     }
 
-    virtual ~FontScalerGM() {
-    }
-
 protected:
 
     SkString onShortName() override {
@@ -30,14 +28,6 @@ protected:
         return SkISize::Make(1450, 750);
     }
 
-    static void rotate_about(SkCanvas* canvas,
-                             SkScalar degrees,
-                             SkScalar px, SkScalar py) {
-        canvas->translate(px, py);
-        canvas->rotate(degrees);
-        canvas->translate(-px, -py);
-    }
-
     void onDraw(SkCanvas* canvas) override {
         SkPaint paint;
 
@@ -59,7 +49,7 @@ protected:
                 SkAutoCanvasRestore acr(canvas, true);
                 canvas->translate(SkIntToScalar(50 + i * 230),
                                   SkIntToScalar(20));
-                rotate_about(canvas, SkIntToScalar(i * 5), x, y * 10);
+                sk_tool_utils::rotate_about(canvas, SkIntToScalar(i * 5), x, y * 10);
 
                 {
                     SkPaint p;