Fix a bunch of warnings, mainly around rowBytes.

My recent change changed the way SkBitmap::fRowBytes is stored,
and parameter/return values referring to rowBytes were changed
to type size_t. Change the storage back, and eliminate warnings
resulting from returning a size_t.

Review URL: https://codereview.appspot.com/7396059

git-svn-id: http://skia.googlecode.com/svn/trunk@7855 2bbb7eff-a529-9590-31e7-b0007b416f81
20 files changed