Add sk_sp helpers and switch Blink SkShader clients to the new APIs

third_party/WebKit/Source/platform/graphics/Gradient.h

Index: third_party/WebKit/Source/platform/graphics/Gradient.h
diff --git a/third_party/WebKit/Source/platform/graphics/Gradient.h b/third_party/WebKit/Source/platform/graphics/Gradient.h
index 49e0f740ab84df171045dfcd1c74eab573fa7e70..fdb4663aaecbd9915d51635cf929c8c637fb322b 100644
--- a/third_party/WebKit/Source/platform/graphics/Gradient.h
+++ b/third_party/WebKit/Source/platform/graphics/Gradient.h
@@ -126,7 +126,7 @@ private:
     Gradient(const FloatPoint& p0, const FloatPoint& p1);
     Gradient(const FloatPoint& p0, float r0, const FloatPoint& p1, float r1, float aspectRatio);
 
-    SkShader* shader();
+    PassRefPtr<SkShader> refShader();

[jbroman, 2016/03/17 17:19:13]

nit: didn't notice this earlier, but do we have this addref-and-return pattern
elsewhere? I'd have expected either
- this returning SkShader* (and the caller using sk_ref_sp), or
- returning "const RefPtr<SkShader>&" (well, that's the shared_ptr-like pattern,
but we don't do this elsewhere in Blink), or
- having the method be "void updateShader()" and having the caller know that the
result is in m_shader (since it's in this class)

TBH, though, I don't feel strongly, especially since I lgtmed the earlier patch
with this. So if you like it the way it is, you can land without addressing this
nit.

[Stephen White, 2016/03/17 17:50:40]

I don't think we have ref...() as a verb elsewhere in Blink, and and that sounds
more like explicit ref/unref to me (which we want to avoid), so let's just
call it shader(), as it was before.

[f(malita), 2016/03/17 18:04:42]

Probably not a common pattern in Blink.  I was planning to refactor this
similarly
to Pattern (which has the lazy logic in applyToPaint and not in the shader
builder)
but didn't want to pollute this CL too much.  Makes sense to leave alone for
now.

Done (switched back to the original rawptr API/your first suggestion).

[f(malita), 2016/03/17 18:04:42]

Done.

     void destroyShader();
 
     void sortStopsIfNecessary();