Remove canvas::NewRaster, and rename surface::NewRasterPMColor to N32Premul

tools/skhello.cpp

Index: tools/skhello.cpp
diff --git a/tools/skhello.cpp b/tools/skhello.cpp
index 55748d2e1bb9b4a2ec5aae35625b97c17b810f91..9f054342a4e719fa404ccfe86242d0100b23d77f 100644
--- a/tools/skhello.cpp
+++ b/tools/skhello.cpp
@@ -33,7 +33,7 @@ static void doDraw(SkCanvas* canvas, const SkPaint& paint, const char text[]) {
 
 static bool do_surface(int w, int h, const char path[], const char text[],
                        const SkPaint& paint) {
-    SkAutoTUnref<SkSurface> surface(SkSurface::NewRasterPMColor(w, h));
+    SkAutoTUnref<SkSurface> surface(SkSurface::NewRasterN32Premul(w, h));
     doDraw(surface->getCanvas(), paint, text);
 
     SkAutoTUnref<SkImage> image(surface->newImageSnapshot());