use some helper Make functions to initialize SkImageInfo

BUG=
R=halcanary@google.com, scroggo@google.com

Author: reed@google.com

Review URL: https://codereview.chromium.org/137993012

git-svn-id: http://skia.googlecode.com/svn/trunk@13081 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/samplecode/SampleFatBits.cpp b/samplecode/SampleFatBits.cpp
index c6fc67f..8b486bd 100644
--- a/samplecode/SampleFatBits.cpp
+++ b/samplecode/SampleFatBits.cpp
@@ -106,9 +106,7 @@
         fInverse.setScale(SK_Scalar1 / zoom, SK_Scalar1 / zoom);
         fShader->setLocalMatrix(fMatrix);
 
-        SkImageInfo info = {
-            width, height, kPMColor_SkColorType, kPremul_SkAlphaType
-        };
+        SkImageInfo info = SkImageInfo::MakeN32Premul(width, height);
         fMinSurface.reset(SkSurface::NewRaster(info));
         info.fWidth *= zoom;
         info.fHeight *= zoom;