ui: Use skia::RefPtr<T> for implicit safe reference counting.

ui/gfx/canvas_mac.mm

Index: ui/gfx/canvas_mac.mm
diff --git a/ui/gfx/canvas_mac.mm b/ui/gfx/canvas_mac.mm
index 2b8f39e6d21f6c386ccba5f9e4fe88ca5b4822a8..12e44ebdbc9302a90829b7551d82f5032db6262f 100644
--- a/ui/gfx/canvas_mac.mm
+++ b/ui/gfx/canvas_mac.mm
@@ -59,11 +59,10 @@ void Canvas::DrawStringWithShadows(const string16& text,
                                    const ShadowValues& shadows) {
   DLOG_IF(WARNING, !shadows.empty()) << "Text shadow not implemented.";
 
-  SkTypeface* typeface = SkTypeface::CreateFromName(font.GetFontName().c_str(),
-                                                    FontTypefaceStyle(font));
+  skia::RefPtr<SkTypeface> typeface = SkTypeface::CreateFromName(

[sky, 2012/12/03 15:28:49]

Is it just me, or is it very mysterious as to when you AdoptRef and when you
don't?

. gfx::CreateGradientShader and skia::CreatePlatformCanvas you don't need to.
. skia::CreatePlatformCanvas you do.
. SkTypeface::CreateFromName you don't.

Can we make all these consistant? If not, I would hope that we're at least
consistent in a particular namespace.

[danakj, 2012/12/03 17:00:19]

Oh, this should adopt. It's based on an old CL, and I can't throw this at bots
until the first one lands. I will fix.

The adopt-fu is much less mysterious, when you create a new skia object and it
returns a pointer, you adopt it there.

I've begun converting the skia:: apis to work with refptrs instead of raw
pointers whenever passing ownership, but CreatePlatformCanvas is tricky since it
is used in WebKit as well, so I didn't change it yet. It still returns a new raw
pointer, so it needs to be adopted by the caller.

+      font.GetFontName().c_str(), FontTypefaceStyle(font));
   SkPaint paint;
-  paint.setTypeface(typeface);
-  typeface->unref();
+  paint.setTypeface(typeface.get());
   paint.setColor(color);
   canvas_->drawText(text.c_str(),
                     text.size() * sizeof(string16::value_type),