srand() + rand() -> SkRandom

rand() makes these two GMs thread-unsafe.  When run concurrently they can
interfere with each other.  Use SkRandom instead to guarantee independence.

BUG=skia:1590
R=jvanverth@google.com

Review URL: https://codereview.chromium.org/24105003

git-svn-id: http://skia.googlecode.com/svn/trunk@11295 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed