ui: Eliminate allocating gfx::Canvas on the heap for every view.

ui/native_theme/common_theme.cc

Index: ui/native_theme/common_theme.cc
diff --git a/ui/native_theme/common_theme.cc b/ui/native_theme/common_theme.cc
index 2b7f84485d4ff886ee40551a399c8d02b6bbd0d5..80f3452d76d822e45f668cc4e78bb3297c71ad49 100644
--- a/ui/native_theme/common_theme.cc
+++ b/ui/native_theme/common_theme.cc
@@ -221,8 +221,7 @@ scoped_ptr<gfx::Canvas> CommonThemeCreateCanvas(SkCanvas* sk_canvas) {
   // scale factor from canvas scale.
   SkMatrix m = sk_canvas->getTotalMatrix();
   float device_scale = static_cast<float>(SkScalarAbs(m.getScaleX()));
-  return make_scoped_ptr(
-      gfx::Canvas::CreateCanvasWithoutScaling(sk_canvas, device_scale));
+  return make_scoped_ptr(new gfx::Canvas(sk_canvas, device_scale));
 }
 
 }  // namespace ui